Systems and methods for content injection

ABSTRACT

The present solution is directed towards a policy-based intermediary that dynamically and flexibly injects content in responses between a client and a server based on one or more policies. The present solution addresses the challenges of injecting content in a client-server transaction. The intermediary determines when and what content to inject into a response of a client-server transaction based on a request and/or response policy. The injected content may include timestamp and/or variable tracking of different events in a client-server transaction. For example, when an intermediary appliance is deployed in a system to accelerate system performance and improve user experience, the appliance may inject content based on policy to monitor the acceleration performance of the deployed appliance.

RELATED APPLICATIONS

This application is a continuation of and claims priority to, and thebenefit of, U.S. Non-provisional application Ser. No. 12/399,493,entitled “Systems and Methods For Content Injection”, filed Mar. 6,2009, which claims the benefit of and priority to U.S. ProvisionalApplication No. 61/034,687, entitled “Systems and Methods For ContentInjection”, filed on Mar. 7, 2008, and which is incorporated herein byreference in its entirety for all purposes.

FIELD OF THE INVENTION

The present application generally relates to data communicationnetworks. In particular, the present application relates to systems andmethods for injecting content into a response coming from a server.

BACKGROUND OF THE INVENTION

An intermediary appliance may be deployed in a data communicationnetwork to accelerate system performance and improve end-userexperience. An end-user's experience in a data communication network isdependent on several factors such as the length of time for the serverto respond to a request, the length of time for the browser to load theweb page, and the length of time to render the dependent content on theweb page. The intermediary appliance may process transactions between aclient and a server. To accelerate performance or improve the end userexperience, the intermediary appliance may change the content of atransaction. However, determining when and how to change the content ofa transaction is challenging.

BRIEF SUMMARY OF THE INVENTION

The present solution is directed towards a policy-based intermediarythat dynamically and flexibly injects content in responses between aclient and a server based on one or more policies. The present solutionaddresses the challenges of injecting content in a client-servertransaction. The intermediary determines when and what content to injectinto a response of a client-server transaction based on a request and/orresponse policy. The injected content may include timestamp and/orvariable tracking of different events in a client-server transaction.For example, when an intermediary appliance is deployed in a system toaccelerate system performance and improve user experience, the appliancemay inject content based on policy to monitor the accelerationperformance of the deployed appliance.

In one aspect, the present application features a method for controllinginjection of content into a response from a server to a client request.The method includes receiving the server response at an intermediary anddetermining, by a policy engine at the intermediary if the responsematches a policy of inserting specified content into the response. Thecontent identifies one or more variables provided by the intermediary.The method also includes modifying the response by the intermediary toinsert the specified content comprising a value of the variableidentified by the intermediary. The method further includes transmittingthe modified response from the intermediary to the client in response ofthe request.

In some embodiments, the method includes determining the time when oneor more of the following events occur: receiving the first, last byte ofthe client request at the intermediary, forwarding the first, last byteof the request from the intermediary to a server, receiving the first,last byte of server response at the intermediary and forwarding thefirst, last byte of the server response from the intermediary to theclient. In some other embodiments, the method also includes storing thevalues of these time instants in appropriate variables identified by thecontent inserted in the response.

In one embodiment, the intermediary provides as a value of a variableone or more of: an identifier of the intermediary, a transactionidentified for the request and the response and a system uptime. Inanother embodiment, a policy specifies if one or more of a HyperTextTransfer Protocol (HTTP) prebody, postbody or header is to be insertedin the server response. In still another embodiment, the policy enginedetermines if a portion of the request, the response or a network packetmatches an expression of a policy.

In one embodiment, the intermediary is an appliance that intercepts andforwards requests and responses between a client and a server. Inanother embodiment, the intermediary is an agent operating on either theclient or the server.

In another aspect, the present application features a method forcontrolling injection of content into a response from a server to aclient request. The method includes receiving a request from a client toa server by an intermediary and determining, by a policy engine at theintermediary if the request matches a policy of inserting specifiedcontent into a response. The content identifies one or more variablesprovided by the intermediary. The method also includes receiving theserver response at the intermediary upon forwarding the client requestto the server and determining, by the intermediary if the responsecorresponds to the request that matched the policy. The method furthercomprises modifying the response by the intermediary to insert contentin accordance with the policy and transmitting the modified response tothe client.

In some embodiments, the method comprises determining the time when oneor more of the following events occur: receiving the first, last byte ofthe client request at the intermediary, forwarding the first, last byteof the request from the intermediary to a server, receiving the first,last byte of server response at the intermediary and forwarding thefirst, last byte of the server response from the intermediary to theclient. In some other embodiments, the method further comprises storingthe values of these time instants in appropriate variables identified bythe content inserted in the response.

In one embodiment, the intermediary provides as a value of a variable,one or more of: an identifier of the intermediary, a transactionidentified for the request and the response and a system uptime. Inanother embodiment, a policy specifies if one or more of a HyperTextTransfer Protocol (HTTP) prebody, postbody or header is to be insertedin the server response. In still another embodiment, the policy enginedetermines if a portion of the request, the response or a network packetmatches an expression of a policy.

BRIEF DESCRIPTION OF THE FIGURES

The foregoing and other objects, aspects, features, and advantages ofthe invention will become more apparent and better understood byreferring to the following description taken in conjunction with theaccompanying drawings, in which:

FIGS. 1A, 1B and 1C are block diagrams of embodiments of a networkenvironment for a client to access a server via one or more appliances;

FIG. 1D is a block diagram of an embodiment of an environment fordelivering a computing environment from a server to a client via anappliance;

FIGS. 1E and 1F are block diagrams of embodiments of a computing device;

FIG. 2A is a block diagram of an embodiment of an appliance foroptimizing, accelerating, load-balancing and routing communicationsbetween a client and a server;

FIG. 2B is a block diagram of another embodiment of an appliance forprocessing communications between a client and a server;

FIG. 3 is a block diagram of an embodiment of a client for communicatingwith a server via the appliance;

FIG. 4A is an embodiment of a system to inject content into a responsecoming from a server to a client.

FIG. 4B is another embodiment of a system to inject content into aresponse coming from a server to a client.

FIG. 4C is still another embodiment of a system to inject content into aresponse coming from a server to a client.

FIG. 5A is an embodiment of the steps in a method to inject content intoa response coming from a server to a client.

FIG. 5B is an embodiment of the steps taken in preparation for contentinjection at an appliance before forwarding a request from a client to aserver.

FIG. 5C is an embodiment of the steps taken at an appliance to injectcontent to a response from a server to a client.

The features and advantages of the present invention will become moreapparent from the detailed description set forth below when taken inconjunction with the drawings, in which like reference charactersidentify corresponding elements throughout. In the drawings, likereference numbers generally indicate identical, functionally similar,and/or structurally similar elements.

DETAILED DESCRIPTION OF THE INVENTION

For purposes of reading the description of the various embodiments ofthe present invention below, the following descriptions of the sectionsof the specification and their respective contents may be helpful:

-   -   Section A describes a network environment and computing        environment useful for practicing an embodiment of the present        invention;    -   Section B describes embodiments of a system and appliance        architecture for accelerating delivery of a computing        environment to a remote user;    -   Section C describes embodiments of a client agent for        accelerating communications between a client and a server; and    -   Section D describes embodiments of systems and methods for        injection content in a client-server transaction.        A. Network and Computing Environment

Prior to discussing the specifics of embodiments of the systems andmethods for injecting content into a server response, it may be helpfulto discuss the network and computing environments in which suchembodiments may be deployed. Referring now to FIG. 1A, an embodiment ofa network environment is depicted. In brief overview, the networkenvironment comprises one or more clients 102 a-102 n (also generallyreferred to as local machine(s) 102, or client(s) 102) in communicationwith one or more servers 106 a-106 n (also generally referred to asserver(s) 106, or remote machine(s) 106) via one or more networks 104,104′ (generally referred to as network 104). In some embodiments, aclient 102 communicates with a server 106 via an appliance 200.

Although FIG. 1A shows a network 104 and a network 104′ between theclients 102 and the servers 106, the clients 102 and the servers 106 maybe on the same network 104. The networks 104 and 104′ can be the sametype of network or different types of networks. The network 104 and/orthe network 104′ can be a local-area network (LAN), such as a companyIntranet, a metropolitan area network (MAN), or a wide area network(WAN), such as the Internet or the World Wide Web. In one embodiment,network 104′ may be a private network and network 104 may be a publicnetwork. In some embodiments, network 104 may be a private network andnetwork 104′ a public network. In another embodiment, networks 104 and104′ may both be private networks. In some embodiments, clients 102 maybe located at a branch office of a corporate enterprise communicatingvia a WAN connection over the network 104 to the servers 106 located ata corporate data center.

The network 104 and/or 104′ be any type and/or form of network and mayinclude any of the following: a point to point network, a broadcastnetwork, a wide area network, a local area network, a telecommunicationsnetwork, a data communication network, a computer network, an ATM(Asynchronous Transfer Mode) network, a SONET (Synchronous OpticalNetwork) network, a SDH (Synchronous Digital Hierarchy) network, awireless network and a wireline network. In some embodiments, thenetwork 104 may comprise a wireless link, such as an infrared channel orsatellite band. The topology of the network 104 and/or 104′ may be abus, star, or ring network topology. The network 104 and/or 104′ andnetwork topology may be of any such network or network topology as knownto those ordinarily skilled in the art capable of supporting theoperations described herein.

As shown in FIG. 1A, the appliance 200, which also may be referred to asan interface unit 200 or gateway 200, is shown between the networks 104and 104′. In some embodiments, the appliance 200 may be located onnetwork 104. For example, a branch office of a corporate enterprise maydeploy an appliance 200 at the branch office. In other embodiments, theappliance 200 may be located on network 104′. For example, an appliance200 may be located at a corporate data center. In yet anotherembodiment, a plurality of appliances 200 may be deployed on network104. In some embodiments, a plurality of appliances 200 may be deployedon network 104′. In one embodiment, a first appliance 200 communicateswith a second appliance 200′. In other embodiments, the appliance 200could be a part of any client 102 or server 106 on the same or differentnetwork 104,104′ as the client 102. One or more appliances 200 may belocated at any point in the network or network communications pathbetween a client 102 and a server 106.

In some embodiments, the appliance 200 comprises any of the networkdevices manufactured by Citrix Systems, Inc. of Ft. Lauderdale, Fla.,referred to as Citrix NetScaler devices. In other embodiments, theappliance 200 includes any of the product embodiments referred to asWebAccelerator and BigIP manufactured by F5 Networks, Inc. of Seattle,Wash. In another embodiment, the appliance 205 includes any of the DXacceleration device platforms and/or the SSL VPN series of devices, suchas SA 700, SA 2000, SA 4000, and SA 6000 devices manufactured by JuniperNetworks, Inc. of Sunnyvale, Calif. In yet another embodiment, theappliance 200 includes any application acceleration and/or securityrelated appliances and/or software manufactured by Cisco Systems, Inc.of San Jose, Calif., such as the Cisco ACE Application Control EngineModule service software and network modules, and Cisco AVS SeriesApplication Velocity System.

In one embodiment, the system may include multiple, logically-groupedservers 106. In these embodiments, the logical group of servers may bereferred to as a server farm 38. In some of these embodiments, theserves 106 may be geographically dispersed. In some cases, a farm 38 maybe administered as a single entity. In other embodiments, the serverfarm 38 comprises a plurality of server farms 38. In one embodiment, theserver farm executes one or more applications on behalf of one or moreclients 102.

The servers 106 within each farm 38 can be heterogeneous. One or more ofthe servers 106 can operate according to one type of operating systemplatform (e.g., WINDOWS NT, manufactured by Microsoft Corp. of Redmond,Wash.), while one or more of the other servers 106 can operate onaccording to another type of operating system platform (e.g., Unix orLinux). The servers 106 of each farm 38 do not need to be physicallyproximate to another server 106 in the same farm 38. Thus, the group ofservers 106 logically grouped as a farm 38 may be interconnected using awide-area network (WAN) connection or medium-area network (MAN)connection. For example, a farm 38 may include servers 106 physicallylocated in different continents or different regions of a continent,country, state, city, campus, or room. Data transmission speeds betweenservers 106 in the farm 38 can be increased if the servers 106 areconnected using a local-area network (LAN) connection or some form ofdirect connection.

Servers 106 may be referred to as a file server, application server, webserver, proxy server, or gateway server. In some embodiments, a server106 may have the capacity to function as either an application server oras a master application server. In one embodiment, a server 106 mayinclude an Active Directory. The clients 102 may also be referred to asclient nodes or endpoints. In some embodiments, a client 102 has thecapacity to function as both a client node seeking access toapplications on a server and as an application server providing accessto hosted applications for other clients 102 a-102 n.

In some embodiments, a client 102 communicates with a server 106. In oneembodiment, the client 102 communicates directly with one of the servers106 in a farm 38. In another embodiment, the client 102 executes aprogram neighborhood application to communicate with a server 106 in afarm 38. In still another embodiment, the server 106 provides thefunctionality of a master node. In some embodiments, the client 102communicates with the server 106 in the farm 38 through a network 104.Over the network 104, the client 102 can, for example, request executionof various applications hosted by the servers 106 a-106 n in the farm 38and receive output of the results of the application execution fordisplay. In some embodiments, only the master node provides thefunctionality required to identify and provide address informationassociated with a server 106′ hosting a requested application.

In one embodiment, the server 106 provides functionality of a webserver. In another embodiment, the server 106 a receives requests fromthe client 102, forwards the requests to a second server 106 b andresponds to the request by the client 102 with a response to the requestfrom the server 106 b. In still another embodiment, the server 106acquires an enumeration of applications available to the client 102 andaddress information associated with a server 106 hosting an applicationidentified by the enumeration of applications. In yet anotherembodiment, the server 106 presents the response to the request to theclient 102 using a web interface. In one embodiment, the client 102communicates directly with the server 106 to access the identifiedapplication. In another embodiment, the client 102 receives applicationoutput data, such as display data, generated by an execution of theidentified application on the server 106.

Referring now to FIG. 1B, an embodiment of a network environmentdeploying multiple appliances 200 is depicted. A first appliance 200 maybe deployed on a first network 104 and a second appliance 200′ on asecond network 104′. For example a corporate enterprise may deploy afirst appliance 200 at a branch office and a second appliance 200′ at adata center. In another embodiment, the first appliance 200 and secondappliance 200′ are deployed on the same network 104 or network 104. Forexample, a first appliance 200 may be deployed for a first server farm38, and a second appliance 200 may be deployed for a second server farm38′. In another example, a first appliance 200 may be deployed at afirst branch office while the second appliance 200′ is deployed at asecond branch office′. In some embodiments, the first appliance 200 andsecond appliance 200′ work in cooperation or in conjunction with eachother to accelerate network traffic or the delivery of application anddata between a client and a server

Referring now to FIG. 1C, another embodiment of a network environmentdeploying the appliance 200 with one or more other types of appliances,such as between one or more WAN optimization appliance 205, 205′ isdepicted. For example a first WAN optimization appliance 205 is shownbetween networks 104 and 104′ and s second WAN optimization appliance205′ may be deployed between the appliance 200 and one or more servers106. By way of example, a corporate enterprise may deploy a first WANoptimization appliance 205 at a branch office and a second WANoptimization appliance 205′ at a data center. In some embodiments, theappliance 205 may be located on network 104′. In other embodiments, theappliance 205′ may be located on network 104. In some embodiments, theappliance 205′ may be located on network 104′ or network 104″. In oneembodiment, the appliance 205 and 205′ are on the same network. Inanother embodiment, the appliance 205 and 205′ are on differentnetworks. In another example, a first WAN optimization appliance 205 maybe deployed for a first server farm 38 and a second WAN optimizationappliance 205′ for a second server farm 38′

In one embodiment, the appliance 205 is a device for accelerating,optimizing or otherwise improving the performance, operation, or qualityof service of any type and form of network traffic, such as traffic toand/or from a WAN connection. In some embodiments, the appliance 205 isa performance enhancing proxy. In other embodiments, the appliance 205is any type and form of WAN optimization or acceleration device,sometimes also referred to as a WAN optimization controller. In oneembodiment, the appliance 205 is any of the product embodiments referredto as WANScaler manufactured by Citrix Systems, Inc. of Ft. Lauderdale,Fla. In other embodiments, the appliance 205 includes any of the productembodiments referred to as BIG-IP link controller and WANjetmanufactured by F5 Networks, Inc. of Seattle, Wash. In anotherembodiment, the appliance 205 includes any of the WX and WXC WANacceleration device platforms manufactured by Juniper Networks, Inc. ofSunnyvale, Calif. In some embodiments, the appliance 205 includes any ofthe steelhead line of WAN optimization appliances manufactured byRiverbed Technology of San Francisco, Calif. In other embodiments, theappliance 205 includes any of the WAN related devices manufactured byExpand Networks Inc. of Roseland, N.J. In one embodiment, the appliance205 includes any of the WAN related appliances manufactured by PacketeerInc. of Cupertino, Calif., such as the PacketShaper, iShared, and SkyXproduct embodiments provided by Packeteer. In yet another embodiment,the appliance 205 includes any WAN related appliances and/or softwaremanufactured by Cisco Systems, Inc. of San Jose, Calif., such as theCisco Wide Area Network Application Services software and networkmodules, and Wide Area Network engine appliances.

In one embodiment, the appliance 205 provides application and dataacceleration services for branch-office or remote offices. In oneembodiment, the appliance 205 includes optimization of Wide Area FileServices (WAFS). In another embodiment, the appliance 205 acceleratesthe delivery of files, such as via the Common Internet File System(CIFS) protocol. In other embodiments, the appliance 205 providescaching in memory and/or storage to accelerate delivery of applicationsand data. In one embodiment, the appliance 205 provides compression ofnetwork traffic at any level of the network stack or at any protocol ornetwork layer. In another embodiment, the appliance 205 providestransport layer protocol optimizations, flow control, performanceenhancements or modifications and/or management to accelerate deliveryof applications and data over a WAN connection. For example, in oneembodiment, the appliance 205 provides Transport Control Protocol (TCP)optimizations. In other embodiments, the appliance 205 providesoptimizations, flow control, performance enhancements or modificationsand/or management for any session or application layer protocol.

In another embodiment, the appliance 205 encoded any type and form ofdata or information into custom or standard TCP and/or IP header fieldsor option fields of network packet to announce presence, functionalityor capability to another appliance 205′. In another embodiment, anappliance 205′ may communicate with another appliance 205′ using dataencoded in both TCP and/or IP header fields or options. For example, theappliance may use TCP option(s) or IP header fields or options tocommunicate one or more parameters to be used by the appliances 205,205′ in performing functionality, such as WAN acceleration, or forworking in conjunction with each other.

In some embodiments, the appliance 200 preserves any of the informationencoded in TCP and/or IP header and/or option fields communicatedbetween appliances 205 and 205′. For example, the appliance 200 mayterminate a transport layer connection traversing the appliance 200,such as a transport layer connection from between a client and a servertraversing appliances 205 and 205′. In one embodiment, the appliance 200identifies and preserves any encoded information in a transport layerpacket transmitted by a first appliance 205 via a first transport layerconnection and communicates a transport layer packet with the encodedinformation to a second appliance 205′ via a second transport layerconnection.

Referring now to FIG. 1D, a network environment for delivering and/oroperating a computing environment on a client 102 is depicted. In someembodiments, a server 106 includes an application delivery system 190for delivering a computing environment or an application and/or datafile to one or more clients 102. In brief overview, a client 10 is incommunication with a server 106 via network 104, 104′ and appliance 200.For example, the client 102 may reside in a remote office of a company,e.g., a branch office, and the server 106 may reside at a corporate datacenter. The client 102 comprises a client agent 120, and a computingenvironment 15. The computing environment 15 may execute or operate anapplication that accesses, processes or uses a data file. The computingenvironment 15, application and/or data file may be delivered via theappliance 200 and/or the server 106.

In some embodiments, the appliance 200 accelerates delivery of acomputing environment 15, or any portion thereof, to a client 102. Inone embodiment, the appliance 200 accelerates the delivery of thecomputing environment 15 by the application delivery system 190. Forexample, the embodiments described herein may be used to acceleratedelivery of a streaming application and data file processable by theapplication from a central corporate data center to a remote userlocation, such as a branch office of the company. In another embodiment,the appliance 200 accelerates transport layer traffic between a client102 and a server 106. The appliance 200 may provide accelerationtechniques for accelerating any transport layer payload from a server106 to a client 102, such as: 1) transport layer connection pooling, 2)transport layer connection multiplexing, 3) transport control protocolbuffering, 4) compression and 5) caching. In some embodiments, theappliance 200 provides load balancing of servers 106 in responding torequests from clients 102. In other embodiments, the appliance 200 actsas a proxy or access server to provide access to the one or more servers106. In another embodiment, the appliance 200 provides a secure virtualprivate network connection from a first network 104 of the client 102 tothe second network 104′ of the server 106, such as an SSL VPNconnection. It yet other embodiments, the appliance 200 providesapplication firewall security, control and management of the connectionand communications between a client 102 and a server 106.

In some embodiments, the application delivery management system 190provides application delivery techniques to deliver a computingenvironment to a desktop of a user, remote or otherwise, based on aplurality of execution methods and based on any authentication andauthorization policies applied via a policy engine 195. With thesetechniques, a remote user may obtain a computing environment and accessto server stored applications and data files from any network connecteddevice 100. In one embodiment, the application delivery system 190 mayreside or execute on a server 106. In another embodiment, theapplication delivery system 190 may reside or execute on a plurality ofservers 106 a-106 n. In some embodiments, the application deliverysystem 190 may execute in a server farm 38. In one embodiment, theserver 106 executing the application delivery system 190 may also storeor provide the application and data file. In another embodiment, a firstset of one or more servers 106 may execute the application deliverysystem 190, and a different server 106 n may store or provide theapplication and data file. In some embodiments, each of the applicationdelivery system 190, the application, and data file may reside or belocated on different servers. In yet another embodiment, any portion ofthe application delivery system 190 may reside, execute or be stored onor distributed to the appliance 200, or a plurality of appliances.

The client 102 may include a computing environment 15 for executing anapplication that uses or processes a data file. The client 102 vianetworks 104, 104′ and appliance 200 may request an application and datafile from the server 106. In one embodiment, the appliance 200 mayforward a request from the client 102 to the server 106. For example,the client 102 may not have the application and data file stored oraccessible locally. In response to the request, the application deliverysystem 190 and/or server 106 may deliver the application and data fileto the client 102. For example, in one embodiment, the server 106 maytransmit the application as an application stream to operate incomputing environment 15 on client 102.

In some embodiments, the application delivery system 190 comprises anyportion of the Citrix Access Suite™ by Citrix Systems, Inc., such as theMetaFrame or Citrix Presentation Server™ and/or any of the Microsoft®Windows Terminal Services manufactured by the Microsoft Corporation. Inone embodiment, the application delivery system 190 may deliver one ormore applications to clients 102 or users via a remote-display protocolor otherwise via remote-based or server-based computing. In anotherembodiment, the application delivery system 190 may deliver one or moreapplications to clients or users via steaming of the application.

In one embodiment, the application delivery system 190 includes a policyengine 195 for controlling and managing the access to, selection ofapplication execution methods and the delivery of applications. In someembodiments, the policy engine 195 determines the one or moreapplications a user or client 102 may access. In another embodiment, thepolicy engine 195 determines how the application should be delivered tothe user or client 102, e.g., the method of execution. In someembodiments, the application delivery system 190 provides a plurality ofdelivery techniques from which to select a method of applicationexecution, such as a server-based computing, streaming or delivering theapplication locally to the client 102 for local execution.

In one embodiment, a client 102 requests execution of an applicationprogram and the application delivery system 190 comprising a server 106selects a method of executing the application program. In someembodiments, the server 106 receives credentials from the client 102. Inanother embodiment, the server 106 receives a request for an enumerationof available applications from the client 102. In one embodiment, inresponse to the request or receipt of credentials, the applicationdelivery system 190 enumerates a plurality of application programsavailable to the client 102. The application delivery system 190receives a request to execute an enumerated application. The applicationdelivery system 190 selects one of a predetermined number of methods forexecuting the enumerated application, for example, responsive to apolicy of a policy engine. The application delivery system 190 mayselect a method of execution of the application enabling the client 102to receive application-output data generated by execution of theapplication program on a server 106. The application delivery system 190may select a method of execution of the application enabling the localmachine 10 to execute the application program locally after retrieving aplurality of application files comprising the application. In yetanother embodiment, the application delivery system 190 may select amethod of execution of the application to stream the application via thenetwork 104 to the client 102.

A client 102 may execute, operate or otherwise provide an application,which can be any type and/or form of software, program, or executableinstructions such as any type and/or form of web browser, web-basedclient, client-server application, a thin-client computing client, anActiveX control, or a Java applet, or any other type and/or form ofexecutable instructions capable of executing on client 102. In someembodiments, the application may be a server-based or a remote-basedapplication executed on behalf of the client 102 on a server 106. In oneembodiment, the server 106 may display output to the client 102 usingany thin-client or remote-display protocol, such as the IndependentComputing Architecture (ICA) protocol manufactured by Citrix Systems,Inc. of Ft. Lauderdale, Fla. or the Remote Desktop Protocol (RDP)manufactured by the Microsoft Corporation of Redmond, Wash. Theapplication can use any type of protocol and it can be, for example, anHTTP client, an FTP client, an Oscar client, or a Telnet client. Inother embodiments, the application comprises any type of softwarerelated to VoIP communications, such as a soft IP telephone. In furtherembodiments, the application comprises any application related toreal-time data communications, such as applications for streaming videoand/or audio.

In some embodiments, the server 106 or a server farm 38 may be runningone or more applications, such as an application providing a thin-clientcomputing or remote display presentation application. In one embodiment,the server 106 or server farm 38 executes as an application, any portionof the Citrix Access Suite™ by Citrix Systems, Inc., such as theMetaFrame or Citrix Presentation Server™, and/or any of the Microsoft®Windows Terminal Services manufactured by the Microsoft Corporation. Inone embodiment, the application is an ICA client, developed by CitrixSystems, Inc. of Fort Lauderdale, Fla. In other embodiments, theapplication includes a Remote Desktop (RDP) client, developed byMicrosoft Corporation of Redmond, Wash. Also, the server 106 may run anapplication, which for example, may be an application server providingemail services such as Microsoft Exchange manufactured by the MicrosoftCorporation of Redmond, Wash., a web or Internet server, or a desktopsharing server, or a collaboration server. In some embodiments, any ofthe applications may comprise any type of hosted service or products,such as GoToMeeting™ provided by Citrix Online Division, Inc. of SantaBarbara, Calif., WebEx™ provided by WebEx, Inc. of Santa Clara, Calif.,or Microsoft Office Live Meeting provided by Microsoft Corporation ofRedmond, Wash.

Still referring to FIG. 1D, an embodiment of the network environment mayinclude a monitoring server 106A. The monitoring server 106A may includeany type and form performance monitoring service 198. The performancemonitoring service 198 may include monitoring, measurement and/ormanagement software and/or hardware, including data collection,aggregation, analysis, management and reporting. In one embodiment, theperformance monitoring service 198 includes one or more monitoringagents 197. The monitoring agent 197 includes any software, hardware orcombination thereof for performing monitoring, measurement and datacollection activities on a device, such as a client 102, server 106 oran appliance 200, 205. In some embodiments, the monitoring agent 197includes any type and form of script, such as Visual Basic script, orJavascript. In one embodiment, the monitoring agent 197 executestransparently to any application and/or user of the device. In someembodiments, the monitoring agent 197 is installed and operatedunobtrusively to the application or client. In yet another embodiment,the monitoring agent 197 is installed and operated without anyinstrumentation for the application or device.

In some embodiments, the monitoring agent 197 monitors, measures andcollects data on a predetermined frequency. In other embodiments, themonitoring agent 197 monitors, measures and collects data based upondetection of any type and form of event. For example, the monitoringagent 197 may collect data upon detection of a request for a web page orreceipt of an HTTP response. In another example, the monitoring agent197 may collect data upon detection of any user input events, such as amouse click. The monitoring agent 197 may report or provide anymonitored, measured or collected data to the monitoring service 198. Inone embodiment, the monitoring agent 197 transmits information to themonitoring service 198 according to a schedule or a predeterminedfrequency. In another embodiment, the monitoring agent 197 transmitsinformation to the monitoring service 198 upon detection of an event.

In some embodiments, the monitoring service 198 and/or monitoring agent197 performs monitoring and performance measurement of any networkresource or network infrastructure element, such as a client, server,server farm, appliance 200, appliance 205, or network connection. In oneembodiment, the monitoring service 198 and/or monitoring agent 197performs monitoring and performance measurement of any transport layerconnection, such as a TCP or UDP connection. In another embodiment, themonitoring service 198 and/or monitoring agent 197 monitors and measuresnetwork latency. In yet one embodiment, the monitoring service 198and/or monitoring agent 197 monitors and measures bandwidth utilization.

In other embodiments, the monitoring service 198 and/or monitoring agent197 monitors and measures end-user response times. In some embodiments,the monitoring service 198 performs monitoring and performancemeasurement of an application. In another embodiment, the monitoringservice 198 and/or monitoring agent 197 performs monitoring andperformance measurement of any session or connection to the application.In one embodiment, the monitoring service 198 and/or monitoring agent197 monitors and measures performance of a browser. In anotherembodiment, the monitoring service 198 and/or monitoring agent 197monitors and measures performance of HTTP based transactions. In someembodiments, the monitoring service 198 and/or monitoring agent 197monitors and measures performance of a Voice over IP (VoIP) applicationor session. In other embodiments, the monitoring service 198 and/ormonitoring agent 197 monitors and measures performance of a remotedisplay protocol application, such as an ICA client or RDP client. Inyet another embodiment, the monitoring service 198 and/or monitoringagent 197 monitors and measures performance of any type and form ofstreaming media. In still a further embodiment, the monitoring service198 and/or monitoring agent 197 monitors and measures performance of ahosted application or a Software-As-A-Service (SaaS) delivery model.

In some embodiments, the monitoring service 198 and/or monitoring agent197 performs monitoring and performance measurement of one or moretransactions, requests or responses related to application. In otherembodiments, the monitoring service 198 and/or monitoring agent 197monitors and measures any portion of an application layer stack, such asany .NET or J2EE calls. In one embodiment, the monitoring service 198and/or monitoring agent 197 monitors and measures database or SQLtransactions. In yet another embodiment, the monitoring service 198and/or monitoring agent 197 monitors and measures any method, functionor application programming interface (API) call.

In one embodiment, the monitoring service 198 and/or monitoring agent197 performs monitoring and performance measurement of a delivery ofapplication and/or data from a server to a client via one or moreappliances, such as appliance 200 and/or appliance 205. In someembodiments, the monitoring service 198 and/or monitoring agent 197monitors and measures performance of delivery of a virtualizedapplication. In other embodiments, the monitoring service 198 and/ormonitoring agent 197 monitors and measures performance of delivery of astreaming application. In another embodiment, the monitoring service 198and/or monitoring agent 197 monitors and measures performance ofdelivery of a desktop application to a client and/or the execution ofthe desktop application on the client. In another embodiment, themonitoring service 198 and/or monitoring agent 197 monitors and measuresperformance of a client/server application.

In one embodiment, the monitoring service 198 and/or monitoring agent197 is designed and constructed to provide application performancemanagement for the application delivery system 190. For example, themonitoring service 198 and/or monitoring agent 197 may monitor, measureand manage the performance of the delivery of applications via theCitrix Presentation Server. In this example, the monitoring service 198and/or monitoring agent 197 monitors individual ICA sessions. Themonitoring service 198 and/or monitoring agent 197 may measure the totaland per session system resource usage, as well as application andnetworking performance. The monitoring service 198 and/or monitoringagent 197 may identify the active servers for a given user and/or usersession. In some embodiments, the monitoring service 198 and/ormonitoring agent 197 monitors back-end connections between theapplication delivery system 190 and an application and/or databaseserver. The monitoring service 198 and/or monitoring agent 197 maymeasure network latency, delay and volume per user-session or ICAsession.

In some embodiments, the monitoring service 198 and/or monitoring agent197 measures and monitors memory usage for the application deliverysystem 190, such as total memory usage, per user session and/or perprocess. In other embodiments, the monitoring service 198 and/ormonitoring agent 197 measures and monitors CPU usage the applicationdelivery system 190, such as total CPU usage, per user session and/orper process. In another embodiments, the monitoring service 198 and/ormonitoring agent 197 measures and monitors the time required to log-into an application, a server, or the application delivery system, such asCitrix Presentation Server. In one embodiment, the monitoring service198 and/or monitoring agent 197 measures and monitors the duration auser is logged into an application, a server, or the applicationdelivery system 190. In some embodiments, the monitoring service 198and/or monitoring agent 197 measures and monitors active and inactivesession counts for an application, server or application delivery systemsession. In yet another embodiment, the monitoring service 198 and/ormonitoring agent 197 measures and monitors user session latency.

In yet further embodiments, the monitoring service 198 and/or monitoringagent 197 measures and monitors measures and monitors any type and formof server metrics. In one embodiment, the monitoring service 198 and/ormonitoring agent 197 measures and monitors metrics related to systemmemory, CPU usage, and disk storage. In another embodiment, themonitoring service 198 and/or monitoring agent 197 measures and monitorsmetrics related to page faults, such as page faults per second. In otherembodiments, the monitoring service 198 and/or monitoring agent 197measures and monitors round-trip time metrics. In yet anotherembodiment, the monitoring service 198 and/or monitoring agent 197measures and monitors metrics related to application crashes, errorsand/or hangs.

In some embodiments, the monitoring service 198 and monitoring agent 198includes any of the product embodiments referred to as EdgeSightmanufactured by Citrix Systems, Inc. of Ft. Lauderdale, Fla. In anotherembodiment, the performance monitoring service 198 and/or monitoringagent 198 includes any portion of the product embodiments referred to asthe TrueView product suite manufactured by the Symphoniq Corporation ofPalo Alto, Calif. In one embodiment, the performance monitoring service198 and/or monitoring agent 198 includes any portion of the productembodiments referred to as the TeaLeaf CX product suite manufactured bythe TeaLeaf Technology Inc. of San Francisco, Calif. In otherembodiments, the performance monitoring service 198 and/or monitoringagent 198 includes any portion of the business service managementproducts, such as the BMC Performance Manager and Patrol products,manufactured by BMC Software, Inc. of Houston, Tex.

The client 102, server 106, and appliance 200 may be deployed as and/orexecuted on any type and form of computing device, such as a computer,network device or appliance capable of communicating on any type andform of network and performing the operations described herein. FIGS. 1Eand 1F depict block diagrams of a computing device 100 useful forpracticing an embodiment of the client 102, server 106 or appliance 200.As shown in FIGS. 1E and 1F, each computing device 100 includes acentral processing unit 101, and a main memory unit 122. As shown inFIG. 1E, a computing device 100 may include a visual display device 124,a keyboard 126 and/or a pointing device 127, such as a mouse. Eachcomputing device 100 may also include additional optional elements, suchas one or more input/output devices 130 a-130 b (generally referred tousing reference numeral 130), and a cache memory 140 in communicationwith the central processing unit 101.

The central processing unit 101 is any logic circuitry that responds toand processes instructions fetched from the main memory unit 122. Inmany embodiments, the central processing unit is provided by amicroprocessor unit, such as: those manufactured by Intel Corporation ofMountain View, Calif.; those manufactured by Motorola Corporation ofSchaumburg, Ill.; those manufactured by Transmeta Corporation of SantaClara, Calif.; the RS/6000 processor, those manufactured byInternational Business Machines of White Plains, N.Y.; or thosemanufactured by Advanced Micro Devices of Sunnyvale, Calif. Thecomputing device 100 may be based on any of these processors, or anyother processor capable of operating as described herein.

Main memory unit 122 may be one or more memory chips capable of storingdata and allowing any storage location to be directly accessed by themicroprocessor 101, such as Static random access memory (SRAM), BurstSRAM or SynchBurst SRAM (BSRAM), Dynamic random access memory (DRAM),Fast Page Mode DRAM (FPM DRAM), Enhanced DRAM (EDRAM), Extended DataOutput RAM (EDO RAM), Extended Data Output DRAM (EDO DRAM), BurstExtended Data Output DRAM (BEDO DRAM), Enhanced DRAM (EDRAM),synchronous DRAM (SDRAM), JEDEC SRAM, PC100 SDRAM, Double Data RateSDRAM (DDR SDRAM), Enhanced SDRAM (ESDRAM), SyncLink DRAM (SLDRAM),Direct Rambus DRAM (DRDRAM), or Ferroelectric RAM (FRAM). The mainmemory 122 may be based on any of the above described memory chips, orany other available memory chips capable of operating as describedherein. In the embodiment shown in FIG. 1E, the processor 101communicates with main memory 122 via a system bus 150 (described inmore detail below). FIG. 1E depicts an embodiment of a computing device100 in which the processor communicates directly with main memory 122via a memory port 103. For example, in FIG. 1F the main memory 122 maybe DRDRAM.

FIG. 1F depicts an embodiment in which the main processor 101communicates directly with cache memory 140 via a secondary bus,sometimes referred to as a backside bus. In other embodiments, the mainprocessor 101 communicates with cache memory 140 using the system bus150. Cache memory 140 typically has a faster response time than mainmemory 122 and is typically provided by SRAM, BSRAM, or EDRAM. In theembodiment shown in FIG. 1E, the processor 101 communicates with variousI/O devices 130 via a local system bus 150. Various busses may be usedto connect the central processing unit 101 to any of the I/O devices130, including a VESA VL bus, an ISA bus, an EISA bus, a MicroChannelArchitecture (MCA) bus, a PCI bus, a PCI-X bus, a PCI-Express bus, or aNuBus. For embodiments in which the I/O device is a video display 124,the processor 101 may use an Advanced Graphics Port (AGP) to communicatewith the display 124. FIG. 1F depicts an embodiment of a computer 100 inwhich the main processor 101 communicates directly with I/O device 130via HyperTransport, Rapid I/O, or InfiniBand. FIG. 1F also depicts anembodiment in which local busses and direct communication are mixed: theprocessor 101 communicates with I/O device 130 using a localinterconnect bus while communicating with I/O device 130 directly.

The computing device 100 may support any suitable installation device116, such as a floppy disk drive for receiving floppy disks such as3.5-inch, 5.25-inch disks or ZIP disks, a CD-ROM drive, a CD-R/RW drive,a DVD-ROM drive, tape drives of various formats, USB device, hard-driveor any other device suitable for installing software and programs suchas any client agent 120, or portion thereof. The computing device 100may further comprise a storage device 128, such as one or more hard diskdrives or redundant arrays of independent disks, for storing anoperating system and other related software, and for storing applicationsoftware programs such as any program related to the client agent 120.Optionally, any of the installation devices 116 could also be used asthe storage device 128. Additionally, the operating system and thesoftware can be run from a bootable medium, for example, a bootable CD,such as KNOPPIX®, a bootable CD for GNU/Linux that is available as aGNU/Linux distribution from knoppix.net.

Furthermore, the computing device 100 may include a network interface118 to interface to a Local Area Network (LAN), Wide Area Network (WAN)or the Internet through a variety of connections including, but notlimited to, standard telephone lines, LAN or WAN links (e.g., 802.11,T1, T3, 56kb, X.25), broadband connections (e.g., ISDN, Frame Relay,ATM), wireless connections, or some combination of any or all of theabove. The network interface 118 may comprise a built-in networkadapter, network interface card, PCMCIA network card, card bus networkadapter, wireless network adapter, USB network adapter, modem or anyother device suitable for interfacing the computing device 100 to anytype of network capable of communication and performing the operationsdescribed herein.

A wide variety of I/O devices 130 a-130 n may be present in thecomputing device 100. Input devices include keyboards, mice, trackpads,trackballs, microphones, and drawing tablets. Output devices includevideo displays, speakers, inkjet printers, laser printers, anddye-sublimation printers. The I/O devices 130 may be controlled by anI/O controller 123 as shown in FIG. 1E. The I/O controller may controlone or more I/O devices such as a keyboard 126 and a pointing device127, e.g., a mouse or optical pen. Furthermore, an I/O device may alsoprovide storage 128 and/or an installation medium 116 for the computingdevice 100. In still other embodiments, the computing device 100 mayprovide USB connections to receive handheld USB storage devices such asthe USB Flash Drive line of devices manufactured by Twintech Industry,Inc. of Los Alamitos, Calif.

In some embodiments, the computing device 100 may comprise or beconnected to multiple display devices 124 a-124 n, which each may be ofthe same or different type and/or form. As such, any of the I/O devices130 a-130 n and/or the I/O controller 123 may comprise any type and/orform of suitable hardware, software, or combination of hardware andsoftware to support, enable or provide for the connection and use ofmultiple display devices 124 a-124 n by the computing device 100. Forexample, the computing device 100 may include any type and/or form ofvideo adapter, video card, driver, and/or library to interface,communicate, connect or otherwise use the display devices 124 a-124 n.In one embodiment, a video adapter may comprise multiple connectors tointerface to multiple display devices 124 a-124 n. In other embodiments,the computing device 100 may include multiple video adapters, with eachvideo adapter connected to one or more of the display devices 124 a-124n. In some embodiments, any portion of the operating system of thecomputing device 100 may be configured for using multiple displays 124a-124 n. In other embodiments, one or more of the display devices 124a-124 n may be provided by one or more other computing devices, such ascomputing devices 100 a and 100 b connected to the computing device 100,for example, via a network. These embodiments may include any type ofsoftware designed and constructed to use another computer's displaydevice as a second display device 124 a for the computing device 100.One ordinarily skilled in the art will recognize and appreciate thevarious ways and embodiments that a computing device 100 may beconfigured to have multiple display devices 124 a-124 n.

In further embodiments, an I/O device 130 may be a bridge 170 betweenthe system bus 150 and an external communication bus, such as a USB bus,an Apple Desktop Bus, an RS-232 serial connection, a SCSI bus, aFireWire bus, a FireWire 800 bus, an Ethernet bus, an AppleTalk bus, aGigabit Ethernet bus, an Asynchronous Transfer Mode bus, a HIPPI bus, aSuper HIPPI bus, a SerialPlus bus, a SCI/LAMP bus, a FibreChannel bus,or a Serial Attached small computer system interface bus.

A computing device 100 of the sort depicted in FIGS. 1E and 1F typicallyoperate under the control of operating systems, which control schedulingof tasks and access to system resources. The computing device 100 can berunning any operating system such as any of the versions of theMicrosoft® Windows operating systems, the different releases of the Unixand Linux operating systems, any version of the Mac OS® for Macintoshcomputers, any embedded operating system, any real-time operatingsystem, any open source operating system, any proprietary operatingsystem, any operating systems for mobile computing devices, or any otheroperating system capable of running on the computing device andperforming the operations described herein. Typical operating systemsinclude: WINDOWS 3.x, WINDOWS 95, WINDOWS 98, WINDOWS 2000, WINDOWS NT3.51, WINDOWS NT 4.0, WINDOWS CE, and WINDOWS XP, all of which aremanufactured by Microsoft Corporation of Redmond, Wash.; MacOS,manufactured by Apple Computer of Cupertino, Calif.; OS/2, manufacturedby International Business Machines of Armonk, N.Y.; and Linux, afreely-available operating system distributed by Caldera Corp. of SaltLake City, Utah, or any type and/or form of a Unix operating system,among others.

In other embodiments, the computing device 100 may have differentprocessors, operating systems, and input devices consistent with thedevice. For example, in one embodiment the computer 100 is a Treo 180,270, 1060, 600 or 650 smart phone manufactured by Palm, Inc. In thisembodiment, the Treo smart phone is operated under the control of thePalmOS operating system and includes a stylus input device as well as afive-way navigator device. Moreover, the computing device 100 can be anyworkstation, desktop computer, laptop or notebook computer, server,handheld computer, mobile telephone, any other computer, or other formof computing or telecommunications device that is capable ofcommunication and that has sufficient processor power and memorycapacity to perform the operations described herein.

B. Appliance Architecture

FIG. 2A illustrates an example embodiment of the appliance 200. Thearchitecture of the appliance 200 in FIG. 2A is provided by way ofillustration only and is not intended to be limiting. As shown in FIG.2, appliance 200 comprises a hardware layer 206 and a software layerdivided into a user space 202 and a kernel space 204.

Hardware layer 206 provides the hardware elements upon which programsand services within kernel space 204 and user space 202 are executed.Hardware layer 206 also provides the structures and elements which allowprograms and services within kernel space 204 and user space 202 tocommunicate data both internally and externally with respect toappliance 200. As shown in FIG. 2, the hardware layer 206 includes aprocessing unit 262 for executing software programs and services, amemory 264 for storing software and data, network ports 266 fortransmitting and receiving data over a network, and an encryptionprocessor 260 for performing functions related to Secure Sockets Layerprocessing of data transmitted and received over the network. In someembodiments, the central processing unit 262 may perform the functionsof the encryption processor 260 in a single processor. Additionally, thehardware layer 206 may comprise multiple processors for each of theprocessing unit 262 and the encryption processor 260. The processor 262may include any of the processors 101 described above in connection withFIGS. 1E and 1F. In some embodiments, the central processing unit 262may perform the functions of the encryption processor 260 in a singleprocessor. Additionally, the hardware layer 206 may comprise multipleprocessors for each of the processing unit 262 and the encryptionprocessor 260. For example, in one embodiment, the appliance 200comprises a first processor 262 and a second processor 262′. In otherembodiments, the processor 262 or 262′ comprises a multi-core processor.

Although the hardware layer 206 of appliance 200 is generallyillustrated with an encryption processor 260, processor 260 may be aprocessor for performing functions related to any encryption protocol,such as the Secure Socket Layer (SSL) or Transport Layer Security (TLS)protocol. In some embodiments, the processor 260 may be a generalpurpose processor (GPP), and in further embodiments, may be haveexecutable instructions for performing processing of any securityrelated protocol.

Although the hardware layer 206 of appliance 200 is illustrated withcertain elements in FIG. 2A, the hardware portions or components ofappliance 200 may comprise any type and form of elements, hardware orsoftware, of a computing device, such as the computing device 100illustrated and discussed herein in conjunction with FIGS. 1E and 1F. Insome embodiments, the appliance 200 may comprise a server, gateway,router, switch, bridge or other type of computing or network device, andhave any hardware and/or software elements associated therewith.

The operating system of appliance 200 allocates, manages, or otherwisesegregates the available system memory into kernel space 204 and userspace 204. In example software architecture 200, the operating systemmay be any type and/or form of Unix operating system although theinvention is not so limited. As such, the appliance 200 can be runningany operating system such as any of the versions of the Microsoft®Windows operating systems, the different releases of the Unix and Linuxoperating systems, any version of the Mac OS® for Macintosh computers,any embedded operating system, any network operating system, anyreal-time operating system, any open source operating system, anyproprietary operating system, any operating systems for mobile computingdevices or network devices, or any other operating system capable ofrunning on the appliance 200 and performing the operations describedherein.

The kernel space 204 is reserved for running the kernel 230, includingany device drivers, kernel extensions or other kernel related software.As known to those skilled in the art, the kernel 230 is the core of theoperating system, and provides access, control, and management ofresources and hardware-related elements of the application 104. Inaccordance with an embodiment of the appliance 200, the kernel space 204also includes a number of network services or processes working inconjunction with a cache manager 232, sometimes also referred to as theintegrated cache, the benefits of which are described in detail furtherherein. Additionally, the embodiment of the kernel 230 will depend onthe embodiment of the operating system installed, configured, orotherwise used by the device 200.

In one embodiment, the device 200 comprises one network stack 267, suchas a TCP/IP based stack, for communicating with the client 102 and/orthe server 106. In one embodiment, the network stack 267 is used tocommunicate with a first network, such as network 108, and a secondnetwork 110. In some embodiments, the device 200 terminates a firsttransport layer connection, such as a TCP connection of a client 102,and establishes a second transport layer connection to a server 106 foruse by the client 102, e.g., the second transport layer connection isterminated at the appliance 200 and the server 106. The first and secondtransport layer connections may be established via a single networkstack 267. In other embodiments, the device 200 may comprise multiplenetwork stacks, for example 267 and 267′, and the first transport layerconnection may be established or terminated at one network stack 267,and the second transport layer connection on the second network stack267′. For example, one network stack may be for receiving andtransmitting network packet on a first network, and another networkstack for receiving and transmitting network packets on a secondnetwork. In one embodiment, the network stack 267 comprises a buffer 243for queuing one or more network packets for transmission by theappliance 200.

As shown in FIG. 2, the kernel space 204 includes the cache manager 232,a high-speed layer 2-7 integrated packet engine 240, an encryptionengine 234, a policy engine 236 and multi-protocol compression logic238. Running these components or processes 232, 240, 234, 236 and 238 inkernel space 204 or kernel mode instead of the user space 202 improvesthe performance of each of these components, alone and in combination.Kernel operation means that these components or processes 232, 240, 234,236 and 238 run in the core address space of the operating system of thedevice 200. For example, running the encryption engine 234 in kernelmode improves encryption performance by moving encryption and decryptionoperations to the kernel, thereby reducing the number of transitionsbetween the memory space or a kernel thread in kernel mode and thememory space or a thread in user mode. For example, data obtained inkernel mode may not need to be passed or copied to a process or threadrunning in user mode, such as from a kernel level data structure to auser level data structure. In another aspect, the number of contextswitches between kernel mode and user mode are also reduced.Additionally, synchronization of and communications between any of thecomponents or processes 232, 240, 235, 236 and 238 can be performed moreefficiently in the kernel space 204.

In some embodiments, any portion of the components 232, 240, 234, 236and 238 may run or operate in the kernel space 204, while other portionsof these components 232, 240, 234, 236 and 238 may run or operate inuser space 202. In one embodiment, the appliance 200 uses a kernel-leveldata structure providing access to any portion of one or more networkpackets, for example, a network packet comprising a request from aclient 102 or a response from a server 106. In some embodiments, thekernel-level data structure may be obtained by the packet engine 240 viaa transport layer driver interface or filter to the network stack 267.The kernel-level data structure may comprise any interface and/or dataaccessible via the kernel space 204 related to the network stack 267,network traffic or packets received or transmitted by the network stack267. In other embodiments, the kernel-level data structure may be usedby any of the components or processes 232, 240, 234, 236 and 238 toperform the desired operation of the component or process. In oneembodiment, a component 232, 240, 234, 236 and 238 is running in kernelmode 204 when using the kernel-level data structure, while in anotherembodiment, the component 232, 240, 234, 236 and 238 is running in usermode when using the kernel-level data structure. In some embodiments,the kernel-level data structure may be copied or passed to a secondkernel-level data structure, or any desired user-level data structure.

The cache manager 232 may comprise software, hardware or any combinationof software and hardware to provide cache access, control and managementof any type and form of content, such as objects or dynamicallygenerated objects served by the originating servers 106. The data,objects or content processed and stored by the cache manager 232 maycomprise data in any format, such as a markup language, or communicatedvia any protocol. In some embodiments, the cache manager 232 duplicatesoriginal data stored elsewhere or data previously computed, generated ortransmitted, in which the original data may require longer access timeto fetch, compute or otherwise obtain relative to reading a cache memoryelement. Once the data is stored in the cache memory element, future usecan be made by accessing the cached copy rather than refetching orrecomputing the original data, thereby reducing the access time. In someembodiments, the cache memory element nat comprise a data object inmemory 264 of device 200. In other embodiments, the cache memory elementmay comprise memory having a faster access time than memory 264. Inanother embodiment, the cache memory element may comprise any type andform of storage element of the device 200, such as a portion of a harddisk. In some embodiments, the processing unit 262 may provide cachememory for use by the cache manager 232. In yet further embodiments, thecache manager 232 may use any portion and combination of memory,storage, or the processing unit for caching data, objects, and othercontent.

Furthermore, the cache manager 232 includes any logic, functions, rules,or operations to perform any embodiments of the techniques of theappliance 200 described herein. For example, the cache manager 232includes logic or functionality to invalidate objects based on theexpiration of an invalidation time period or upon receipt of aninvalidation command from a client 102 or server 106. In someembodiments, the cache manager 232 may operate as a program, service,process or task executing in the kernel space 204, and in otherembodiments, in the user space 202. In one embodiment, a first portionof the cache manager 232 executes in the user space 202 while a secondportion executes in the kernel space 204. In some embodiments, the cachemanager 232 can comprise any type of general purpose processor (GPP), orany other type of integrated circuit, such as a Field Programmable GateArray (FPGA), Programmable Logic Device (PLD), or Application SpecificIntegrated Circuit (ASIC).

The policy engine 236 may include, for example, an intelligentstatistical engine or other programmable application(s). In oneembodiment, the policy engine 236 provides a configuration mechanism toallow a user to identifying, specify, define or configure a cachingpolicy. Policy engine 236, in some embodiments, also has access tomemory to support data structures such as lookup tables or hash tablesto enable user-selected caching policy decisions. In other embodiments,the policy engine 236 may comprise any logic, rules, functions oroperations to determine and provide access, control and management ofobjects, data or content being cached by the appliance 200 in additionto access, control and management of security, network traffic, networkaccess, compression or any other function or operation performed by theappliance 200. Further examples of specific caching policies are furtherdescribed herein.

The encryption engine 234 comprises any logic, business rules, functionsor operations for handling the processing of any security relatedprotocol, such as SSL or TLS, or any function related thereto. Forexample, the encryption engine 234 encrypts and decrypts networkpackets, or any portion thereof, communicated via the appliance 200. Theencryption engine 234 may also setup or establish SSL or TLS connectionson behalf of the client 102 a-102 n, server 106 a-106 n, or appliance200. As such, the encryption engine 234 provides offloading andacceleration of SSL processing. In one embodiment, the encryption engine234 uses a tunneling protocol to provide a virtual private networkbetween a client 102 a-102 n and a server 106 a-106 n. In someembodiments, the encryption engine 234 is in communication with theEncryption processor 260. In other embodiments, the encryption engine234 comprises executable instructions running on the Encryptionprocessor 260.

The multi-protocol compression engine 238 comprises any logic, businessrules, function or operations for compressing one or more protocols of anetwork packet, such as any of the protocols used by the network stack267 of the device 200. In one embodiment, multi-protocol compressionengine 238 compresses bi-directionally between clients 102 a-102 n andservers 106 a-106 n any TCP/IP based protocol, including MessagingApplication Programming Interface (MAPI) (email), File Transfer Protocol(FTP), HyperText Transfer Protocol (HTTP), Common Internet File System(CIFS) protocol (file transfer), Independent Computing Architecture(ICA) protocol, Remote Desktop Protocol (RDP), Wireless ApplicationProtocol (WAP), Mobile IP protocol, and Voice Over IP (VoIP) protocol.In other embodiments, multi-protocol compression engine 238 providescompression of Hypertext Markup Language (HTML) based protocols and insome embodiments, provides compression of any markup languages, such asthe Extensible Markup Language (XML). In one embodiment, themulti-protocol compression engine 238 provides compression of anyhigh-performance protocol, such as any protocol designed for appliance200 to appliance 200 communications. In another embodiment, themulti-protocol compression engine 238 compresses any payload of or anycommunication using a modified transport control protocol, such asTransaction TCP (T/TCP), TCP with selection acknowledgements (TCP-SACK),TCP with large windows (TCP-LW), a congestion prediction protocol suchas the TCP-Vegas protocol, and a TCP spoofing protocol.

As such, the multi-protocol compression engine 238 acceleratesperformance for users accessing applications via desktop clients, e.g.,Microsoft Outlook and non-Web thin clients, such as any client launchedby popular enterprise applications like Oracle, SAP and Siebel, and evenmobile clients, such as the Pocket PC. In some embodiments, themulti-protocol compression engine 238 by executing in the kernel mode204 and integrating with packet processing engine 240 accessing thenetwork stack 267 is able to compress any of the protocols carried bythe TCP/IP protocol, such as any application layer protocol.

High speed layer 2-7 integrated packet engine 240, also generallyreferred to as a packet processing engine or packet engine, isresponsible for managing the kernel-level processing of packets receivedand transmitted by appliance 200 via network ports 266. The high speedlayer 2-7 integrated packet engine 240 may comprise a buffer for queuingone or more network packets during processing, such as for receipt of anetwork packet or transmission of a network packer. Additionally, thehigh speed layer 2-7 integrated packet engine 240 is in communicationwith one or more network stacks 267 to send and receive network packetsvia network ports 266. The high speed layer 2-7 integrated packet engine240 works in conjunction with encryption engine 234, cache manager 232,policy engine 236 and multi-protocol compression logic 238. Inparticular, encryption engine 234 is configured to perform SSLprocessing of packets, policy engine 236 is configured to performfunctions related to traffic management such as request-level contentswitching and request-level cache redirection, and multi-protocolcompression logic 238 is configured to perform functions related tocompression and decompression of data.

The high speed layer 2-7 integrated packet engine 240 includes a packetprocessing timer 242. In one embodiment, the packet processing timer 242provides one or more time intervals to trigger the processing ofincoming, i.e., received, or outgoing, i.e., transmitted, networkpackets. In some embodiments, the high speed layer 2-7 integrated packetengine 240 processes network packets responsive to the timer 242. Thepacket processing timer 242 provides any type and form of signal to thepacket engine 240 to notify, trigger, or communicate a time relatedevent, interval or occurrence. In many embodiments, the packetprocessing timer 242 operates in the order of milliseconds, such as forexample 100 ms, 50 ms or 25 ms. For example, in some embodiments, thepacket processing timer 242 provides time intervals or otherwise causesa network packet to be processed by the high speed layer 2-7 integratedpacket engine 240 at a 10 ms time interval, while in other embodiments,at a 5 ms time interval, and still yet in further embodiments, as shortas a 3, 2, or 1 ms time interval. The high speed layer 2-7 integratedpacket engine 240 may be interfaced, integrated or in communication withthe encryption engine 234, cache manager 232, policy engine 236 andmulti-protocol compression engine 238 during operation. As such, any ofthe logic, functions, or operations of the encryption engine 234, cachemanager 232, policy engine 236 and multi-protocol compression logic 238may be performed responsive to the packet processing timer 242 and/orthe packet engine 240. Therefore, any of the logic, functions, oroperations of the encryption engine 234, cache manager 232, policyengine 236 and multi-protocol compression logic 238 may be performed atthe granularity of time intervals provided via the packet processingtimer 242, for example, at a time interval of less than or equal to 10ms. For example, in one embodiment, the cache manager 232 may performinvalidation of any cached objects responsive to the high speed layer2-7 integrated packet engine 240 and/or the packet processing timer 242.In another embodiment, the expiry or invalidation time of a cachedobject can be set to the same order of granularity as the time intervalof the packet processing timer 242, such as at every 10 ms.

In contrast to kernel space 204, user space 202 is the memory area orportion of the operating system used by user mode applications orprograms otherwise running in user mode. A user mode application may notaccess kernel space 204 directly and uses service calls in order toaccess kernel services. As shown in FIG. 2, user space 202 of appliance200 includes a graphical user interface (GUI) 210, a command lineinterface (CLI) 212, shell services 214, health monitoring program 216,and daemon services 218. GUI 210 and CLI 212 provide a means by which asystem administrator or other user can interact with and control theoperation of appliance 200, such as via the operating system of theappliance 200 and either is user space 202 or kernel space 204. The GUI210 may be any type and form of graphical user interface and may bepresented via text, graphical or otherwise, by any type of program orapplication, such as a browser. The CLI 212 may be any type and form ofcommand line or text-based interface, such as a command line provided bythe operating system. For example, the CLI 212 may comprise a shell,which is a tool to enable users to interact with the operating system.In some embodiments, the CLI 212 may be provided via a bash, csh, tcsh,or ksh type shell. The shell services 214 comprises the programs,services, tasks, processes or executable instructions to supportinteraction with the appliance 200 or operating system by a user via theGUI 210 and/or CLI 212.

Health monitoring program 216 is used to monitor, check, report andensure that network systems are functioning properly and that users arereceiving requested content over a network. Health monitoring program216 comprises one or more programs, services, tasks, processes orexecutable instructions to provide logic, rules, functions or operationsfor monitoring any activity of the appliance 200. In some embodiments,the health monitoring program 216 intercepts and inspects any networktraffic passed via the appliance 200. In other embodiments, the healthmonitoring program 216 interfaces by any suitable means and/ormechanisms with one or more of the following: the encryption engine 234,cache manager 232, policy engine 236, multi-protocol compression logic238, packet engine 240, daemon services 218, and shell services 214. Assuch, the health monitoring program 216 may call any applicationprogramming interface (API) to determine a state, status, or health ofany portion of the appliance 200. For example, the health monitoringprogram 216 may ping or send a status inquiry on a periodic basis tocheck if a program, process, service or task is active and currentlyrunning. In another example, the health monitoring program 216 may checkany status, error or history logs provided by any program, process,service or task to determine any condition, status or error with anyportion of the appliance 200.

Daemon services 218 are programs that run continuously or in thebackground and handle periodic service requests received by appliance200. In some embodiments, a daemon service may forward the requests toother programs or processes, such as another daemon service 218 asappropriate. As known to those skilled in the art, a daemon service 218may run unattended to perform continuous or periodic system widefunctions, such as network control, or to perform any desired task. Insome embodiments, one or more daemon services 218 run in the user space202, while in other embodiments, one or more daemon services 218 run inthe kernel space.

Referring now to FIG. 2B, another embodiment of the appliance 200 isdepicted. In brief overview, the appliance 200 provides one or more ofthe following services, functionality or operations: SSL VPNconnectivity 280, switching/load balancing 284, Domain Name Serviceresolution 286, acceleration 288 and an application firewall 290 forcommunications between one or more clients 102 and one or more servers106. Each of the servers 106 may provide one or more network relatedservices 270 a-270 n (referred to as services 270). For example, aserver 106 may provide an HTTP service 270. The appliance 200 comprisesone or more virtual servers or virtual internet protocol servers,referred to as a vServer, VIP server, or just VIP 275 a-275 n (alsoreferred herein as vServer 275). The vServer 275 receives, intercepts orotherwise processes communications between a client 102 and a server 106in accordance with the configuration and operations of the appliance200.

The vServer 275 may comprise software, hardware or any combination ofsoftware and hardware. The vServer 275 may comprise any type and form ofprogram, service, task, process or executable instructions operating inuser mode 202, kernel mode 204 or any combination thereof in theappliance 200. The vServer 275 includes any logic, functions, rules, oroperations to perform any embodiments of the techniques describedherein, such as SSL VPN 280, switching/load balancing 284, Domain NameService resolution 286, acceleration 288 and an application firewall290. In some embodiments, the vServer 275 establishes a connection to aservice 270 of a server 106. The service 275 may comprise any program,application, process, task or set of executable instructions capable ofconnecting to and communicating to the appliance 200, client 102 orvServer 275. For example, the service 275 may comprise a web server,HTTP server, ftp, email or database server. In some embodiments, theservice 270 is a daemon process or network driver for listening,receiving and/or sending communications for an application, such asemail, database or an enterprise application. In some embodiments, theservice 270 may communicate on a specific IP address, or IP address andport.

In some embodiments, the vServer 275 applies one or more policies of thepolicy engine 236 to network communications between the client 102 andserver 106. In one embodiment, the policies are associated with aVServer 275. In another embodiment, the policies are based on a user, ora group of users. In yet another embodiment, a policy is global andapplies to one or more vServers 275 a-275 n, and any user or group ofusers communicating via the appliance 200. In some embodiments, thepolicies of the policy engine have conditions upon which the policy isapplied based on any content of the communication, such as internetprotocol address, port, protocol type, header or fields in a packet, orthe context of the communication, such as user, group of the user,vServer 275, transport layer connection, and/or identification orattributes of the client 102 or server 106.

In other embodiments, the appliance 200 communicates or interfaces withthe policy engine 236 to determine authentication and/or authorizationof a remote user or a remote client 102 to access the computingenvironment 15, application, and/or data file from a server 106. Inanother embodiment, the appliance 200 communicates or interfaces withthe policy engine 236 to determine authentication and/or authorizationof a remote user or a remote client 102 to have the application deliverysystem 190 deliver one or more of the computing environment 15,application, and/or data file. In yet another embodiment, the appliance200 establishes a VPN or SSL VPN connection based on the policy engine's236 authentication and/or authorization of a remote user or a remoteclient 103 In one embodiment, the appliance 102 controls the flow ofnetwork traffic and communication sessions based on policies of thepolicy engine 236. For example, the appliance 200 may control the accessto a computing environment 15, application or data file based on thepolicy engine 236.

In some embodiments, the vServer 275 establishes a transport layerconnection, such as a TCP or UDP connection with a client 102 via theclient agent 120. In one embodiment, the vServer 275 listens for andreceives communications from the client 102. In other embodiments, thevServer 275 establishes a transport layer connection, such as a TCP orUDP connection with a client server 106. In one embodiment, the vServer275 establishes the transport layer connection to an internet protocoladdress and port of a server 270 running on the server 106. In anotherembodiment, the vServer 275 associates a first transport layerconnection to a client 102 with a second transport layer connection tothe server 106. In some embodiments, a vServer 275 establishes a pool oftransport layer connections to a server 106 and multiplexes clientrequests via the pooled transport layer connections.

In some embodiments, the appliance 200 provides a SSL VPN connection 280between a client 102 and a server 106. For example, a client 102 on afirst network 102 requests to establish a connection to a server 106 ona second network 104′. In some embodiments, the second network 104′ isnot routable from the first network 104. In other embodiments, theclient 102 is on a public network 104 and the server 106 is on a privatenetwork 104′, such as a corporate network. In one embodiment, the clientagent 120 intercepts communications of the client 102 on the firstnetwork 104, encrypts the communications, and transmits thecommunications via a first transport layer connection to the appliance200. The appliance 200 associates the first transport layer connectionon the first network 104 to a second transport layer connection to theserver 106 on the second network 104. The appliance 200 receives theintercepted communication from the client agent 102, decrypts thecommunications, and transmits the communication to the server 106 on thesecond network 104 via the second transport layer connection. The secondtransport layer connection may be a pooled transport layer connection.As such, the appliance 200 provides an end-to-end secure transport layerconnection for the client 102 between the two networks 104, 104′.

In one embodiment, the appliance 200 hosts an intranet internet protocolor intranetIP 282 address of the client 102 on the virtual privatenetwork 104. The client 102 has a local network identifier, such as aninternet protocol (IP) address and/or host name on the first network104. When connected to the second network 104′ via the appliance 200,the appliance 200 establishes, assigns or otherwise provides anIntranetIP, which is network identifier, such as IP address and/or hostname, for the client 102 on the second network 104′. The appliance 200listens for and receives on the second or private network 104′ for anycommunications directed towards the client 102 using the client'sestablished IntranetIP 282. In one embodiment, the appliance 200 acts asor on behalf of the client 102 on the second private network 104. Forexample, in another embodiment, a vServer 275 listens for and respondsto communications to the IntranetIP 282 of the client 102. In someembodiments, if a computing device 100 on the second network 104′transmits a request, the appliance 200 processes the request as if itwere the client 102. For example, the appliance 200 may respond to aping to the client's IntranetIP 282. In another example, the appliancemay establish a connection, such as a TCP or UDP connection, withcomputing device 100 on the second network 104 requesting a connectionwith the client's IntranetIP 282.

In some embodiments, the appliance 200 provides one or more of thefollowing acceleration techniques 288 to communications between theclient 102 and server 106: 1) compression; 2) decompression; 3)Transmission Control Protocol pooling; 4) Transmission Control Protocolmultiplexing; 5) Transmission Control Protocol buffering; and 6)caching.

In one embodiment, the appliance 200 relieves servers 106 of much of theprocessing load caused by repeatedly opening and closing transportlayers connections to clients 102 by opening one or more transport layerconnections with each server 106 and maintaining these connections toallow repeated data accesses by clients via the Internet. This techniqueis referred to herein as “connection pooling”.

In some embodiments, in order to seamlessly splice communications from aclient 102 to a server 106 via a pooled transport layer connection, theappliance 200 translates or multiplexes communications by modifyingsequence number and acknowledgment numbers at the transport layerprotocol level. This is referred to as “connection multiplexing”. Insome embodiments, no application layer protocol interaction is required.For example, in the case of an in-bound packet (that is, a packetreceived from a client 102), the source network address of the packet ischanged to that of an output port of appliance 200, and the destinationnetwork address is changed to that of the intended server. In the caseof an outbound packet (that is, one received from a server 106), thesource network address is changed from that of the server 106 to that ofan output port of appliance 200 and the destination address is changedfrom that of appliance 200 to that of the requesting client 102. Thesequence numbers and acknowledgment numbers of the packet are alsotranslated to sequence numbers and acknowledgement expected by theclient 102 on the appliance's 200 transport layer connection to theclient 102. In some embodiments, the packet checksum of the transportlayer protocol is recalculated to account for these translations.

In another embodiment, the appliance 200 provides switching orload-balancing functionality 284 for communications between the client102 and server 106. In some embodiments, the appliance 200 distributestraffic and directs client requests to a server 106 based on layer 4 orapplication-layer request data. In one embodiment, although the networklayer or layer 2 of the network packet identifies a destination server106, the appliance 200 determines the server 106 to distribute thenetwork packet by application information and data carried as payload ofthe transport layer packet. In one embodiment, the health monitoringprograms 216 of the appliance 200 monitor the health of servers todetermine the server 106 for which to distribute a client's request. Insome embodiments, if the appliance 200 detects a server 106 is notavailable or has a load over a predetermined threshold, the appliance200 can direct or distribute client requests to another server 106.

In some embodiments, the appliance 200 acts as a Domain Name Service(DNS) resolver or otherwise provides resolution of a DNS request fromclients 102. In some embodiments, the appliance intercepts' a DNSrequest transmitted by the client 102. In one embodiment, the appliance200 responds to a client's DNS request with an IP address of or hostedby the appliance 200. In this embodiment, the client 102 transmitsnetwork communication for the domain name to the appliance 200. Inanother embodiment, the appliance 200 responds to a client's DNS requestwith an IP address of or hosted by a second appliance 200′. In someembodiments, the appliance 200 responds to a client's DNS request withan IP address of a server 106 determined by the appliance 200.

In yet another embodiment, the appliance 200 provides applicationfirewall functionality 290 for communications between the client 102 andserver 106. In one embodiment, the policy engine 236 provides rules fordetecting and blocking illegitimate requests. In some embodiments, theapplication firewall 290 protects against denial of service (DoS)attacks. In other embodiments, the appliance inspects the content ofintercepted requests to identify and block application-based attacks. Insome embodiments, the rules/policy engine 236 comprises one or moreapplication firewall or security control policies for providingprotections against various classes and types of web or Internet basedvulnerabilities, such as one or more of the following: 1) bufferoverflow, 2) CGI-BIN parameter manipulation, 3) form/hidden fieldmanipulation, 4) forceful browsing, 5) cookie or session poisoning, 6)broken access control list (ACLs) or weak passwords, 7) cross-sitescripting (XSS), 8) command injection, 9) SQL injection, 10) errortriggering sensitive information leak, 11) insecure use of cryptography,12) server misconfiguration, 13) back doors and debug options, 14)website defacement, 15) platform or operating systems vulnerabilities,and 16) zero-day exploits. In an embodiment, the application firewall290 provides HTML form field protection in the form of inspecting oranalyzing the network communication for one or more of the following: 1)required fields are returned, 2) no added field allowed, 3) read-onlyand hidden field enforcement, 4) drop-down list and radio button fieldconformance, and 5) form-field max-length enforcement. In someembodiments, the application firewall 290 ensures cookies are notmodified. In other embodiments, the application firewall 290 protectsagainst forceful browsing by enforcing legal URLs.

In still yet other embodiments, the application firewall 290 protectsany confidential information contained in the network communication. Theapplication firewall 290 may inspect or analyze any networkcommunication in accordance with the rules or polices of the engine 236to identify any confidential information in any field of the networkpacket. In some embodiments, the application firewall 290 identifies inthe network communication one or more occurrences of a credit cardnumber, password, social security number, name, patient code, contactinformation, and age. The encoded portion of the network communicationmay comprise these occurrences or the confidential information. Based onthese occurrences, in one embodiment, the application firewall 290 maytake a policy action on the network communication, such as preventtransmission of the network communication. In another embodiment, theapplication firewall 290 may rewrite, remove or otherwise mask suchidentified occurrence or confidential information.

Still referring to FIG. 2B, the appliance 200 may include a performancemonitoring agent 197 as discussed above in conjunction with FIG. 1D. Inone embodiment, the appliance 200 receives the monitoring agent 197 fromthe monitoring service 1908 or monitoring server 106 as depicted in FIG.1D. In some embodiments, the appliance 200 stores the monitoring agent197 in storage, such as disk, for delivery to any client or server incommunication with the appliance 200. For example, in one embodiment,the appliance 200 transmits the monitoring agent 197 to a client uponreceiving a request to establish a transport layer connection. In otherembodiments, the appliance 200 transmits the monitoring agent 197 uponestablishing the transport layer connection with the client 102. Inanother embodiment, the appliance 200 transmits the monitoring agent 197to the client upon intercepting or detecting a request for a web page.In yet another embodiment, the appliance 200 transmits the monitoringagent 197 to a client or a server in response to a request from themonitoring server 198. In one embodiment, the appliance 200 transmitsthe monitoring agent 197 to a second appliance 200′ or appliance 205.

In other embodiments, the appliance 200 executes the monitoring agent197. In one embodiment, the monitoring agent 197 measures and monitorsthe performance of any application, program, process, service, task orthread executing on the appliance 200. For example, the monitoring agent197 may monitor and measure performance and operation of vServers275A-275N. In another embodiment, the monitoring agent 197 measures andmonitors the performance of any transport layer connections of theappliance 200. In some embodiments, the monitoring agent 197 measuresand monitors the performance of any user sessions traversing theappliance 200. In one embodiment, the monitoring agent 197 measures andmonitors the performance of any virtual private network connectionsand/or sessions traversing the appliance 200, such an SSL VPN session.In still further embodiments, the monitoring agent 197 measures andmonitors the memory, CPU and disk usage and performance of the appliance200. In yet another embodiment, the monitoring agent 197 measures andmonitors the performance of any acceleration technique 288 performed bythe appliance 200, such as SSL offloading, connection pooling andmultiplexing, caching, and compression. In some embodiments, themonitoring agent 197 measures and monitors the performance of any loadbalancing and/or content switching 284 performed by the appliance 200.In other embodiments, the monitoring agent 197 measures and monitors theperformance of application firewall 290 protection and processingperformed by the appliance 200.

C. Client Agent

Referring now to FIG. 3, an embodiment of the client agent 120 isdepicted. The client 102 includes a client agent 120 for establishingand exchanging communications with the appliance 200 and/or server 106via a network 104. In brief overview, the client 102 operates oncomputing device 100 having an operating system with a kernel mode 302and a user mode 303, and a network stack 310 with one or more layers 310a-310 b. The client 102 may have installed and/or execute one or moreapplications. In some embodiments, one or more applications maycommunicate via the network stack 310 to a network 104. One of theapplications, such as a web browser, may also include a first program322. For example, the first program 322 may be used in some embodimentsto install and/or execute the client agent 120, or any portion thereof.The client agent 120 includes an interception mechanism, or interceptor350, for intercepting network communications from the network stack 310from the one or more applications.

The network stack 310 of the client 102 may comprise any type and formof software, or hardware, or any combinations thereof, for providingconnectivity to and communications with a network. In one embodiment,the network stack 310 comprises a software implementation for a networkprotocol suite. The network stack 310 may comprise one or more networklayers, such as any networks layers of the Open Systems Interconnection(OSI) communications model as those skilled in the art recognize andappreciate. As such, the network stack 310 may comprise any type andform of protocols for any of the following layers of the OSI model: 1)physical link layer, 2) data link layer, 3) network layer, 4) transportlayer, 5) session layer, 6) presentation layer, and 7) applicationlayer. In one embodiment, the network stack 310 may comprise a transportcontrol protocol (TCP) over the network layer protocol of the internetprotocol (IP), generally referred to as TCP/IP. In some embodiments, theTCP/IP protocol may be carried over the Ethernet protocol, which maycomprise any of the family of IEEE wide-area-network (WAN) orlocal-area-network (LAN) protocols, such as those protocols covered bythe IEEE 802.3. In some embodiments, the network stack 310 comprises anytype and form of a wireless protocol, such as IEEE 802.11 and/or mobileinternet protocol.

In view of a TCP/IP based network, any TCP/IP based protocol may beused, including Messaging Application Programming Interface (MAPI)(email), File Transfer Protocol (FTP), HyperText Transfer Protocol(HTTP), Common Internet File System (CIFS) protocol (file transfer),Independent Computing Architecture (ICA) protocol, Remote DesktopProtocol (RDP), Wireless Application Protocol (WAP), Mobile IP protocol,and Voice Over IP (VoIP) protocol. In another embodiment, the networkstack 310 comprises any type and form of transport control protocol,such as a modified transport control protocol, for example a TransactionTCP (T/TCP), TCP with selection acknowledgements (TCP-SACK), TCP withlarge windows (TCP-LW), a congestion prediction protocol such as theTCP-Vegas protocol, and a TCP spoofing protocol. In other embodiments,any type and form of user datagram protocol (UDP), such as UDP over IP,may be used by the network stack 310, such as for voice communicationsor real-time data communications.

Furthermore, the network stack 310 may include one or more networkdrivers supporting the one or more layers, such as a TCP driver or anetwork layer driver. The network drivers may be included as part of theoperating system of the computing device 100 or as part of any networkinterface cards or other network access components of the computingdevice 100. In some embodiments, any of the network drivers of thenetwork stack 310 may be customized, modified or adapted to provide acustom or modified portion of the network stack 310 in support of any ofthe techniques described herein. In other embodiments, the accelerationprogram 120 is designed and constructed to operate with or work inconjunction with the network stack 310 installed or otherwise providedby the operating system of the client 102.

The network stack 310 comprises any type and form of interfaces forreceiving, obtaining, providing or otherwise accessing any informationand data related to network communications of the client 102. In oneembodiment, an interface to the network stack 310 comprises anapplication programming interface (API). The interface may also compriseany function call, hooking or filtering mechanism, event or call backmechanism, or any type of interfacing technique. The network stack 310via the interface may receive or provide any type and form of datastructure, such as an object, related to functionality or operation ofthe network stack 310. For example, the data structure may compriseinformation and data related to a network packet or one or more networkpackets. In some embodiments, the data structure comprises a portion ofthe network packet processed at a protocol layer of the network stack310, such as a network packet of the transport layer. In someembodiments, the data structure 325 comprises a kernel-level datastructure, while in other embodiments, the data structure 325 comprisesa user-mode data structure. A kernel-level data structure may comprise adata structure obtained or related to a portion of the network stack 310operating in kernel-mode 302, or a network driver or other softwarerunning in kernel-mode 302, or any data structure obtained or receivedby a service, process, task, thread or other executable instructionsrunning or operating in kernel-mode of the operating system.

Additionally, some portions of the network stack 310 may execute oroperate in kernel-mode 302, for example, the data link or network layer,while other portions execute or operate in user-mode 303, such as anapplication layer of the network stack 310. For example, a first portion310 a of the network stack may provide user-mode access to the networkstack 310 to an application while a second portion 310 a of the networkstack 310 provides access to a network. In some embodiments, a firstportion 310 a of the network stack may comprise one or more upper layersof the network stack 310, such as any of layers 5-7. In otherembodiments, a second portion 310 b of the network stack 310 comprisesone or more lower layers, such as any of layers 1-4. Each of the firstportion 310 a and second portion 310 b of the network stack 310 maycomprise any portion of the network stack 310, at any one or morenetwork layers, in user-mode 203, kernel-mode, 202, or combinationsthereof, or at any portion of a network layer or interface point to anetwork layer or any portion of or interface point to the user-mode 203and kernel-mode 203.

The interceptor 350 may comprise software, hardware, or any combinationof software and hardware. In one embodiment, the interceptor 350intercept a network communication at any point in the network stack 310,and redirects or transmits the network communication to a destinationdesired, managed or controlled by the interceptor 350 or client agent120. For example, the interceptor 350 may intercept a networkcommunication of a network stack 310 of a first network and transmit thenetwork communication to the appliance 200 for transmission on a secondnetwork 104. In some embodiments, the interceptor 350 comprises any typeinterceptor 350 comprises a driver, such as a network driver constructedand designed to interface and work with the network stack 310. In someembodiments, the client agent 120 and/or interceptor 350 operates at oneor more layers of the network stack 310, such as at the transport layer.In one embodiment, the interceptor 350 comprises a filter driver,hooking mechanism, or any form and type of suitable network driverinterface that interfaces to the transport layer of the network stack,such as via the transport driver interface (TDI). In some embodiments,the interceptor 350 interfaces to a first protocol layer, such as thetransport layer and another protocol layer, such as any layer above thetransport protocol layer, for example, an application protocol layer. Inone embodiment, the interceptor 350 may comprise a driver complying withthe Network Driver Interface Specification (NDIS), or a NDIS driver. Inanother embodiment, the interceptor 350 may comprise a min-filter or amini-port driver. In one embodiment, the interceptor 350, or portionthereof, operates in kernel-mode 202. In another embodiment, theinterceptor 350, or portion thereof, operates in user-mode 203. In someembodiments, a portion of the interceptor 350 operates in kernel-mode202 while another portion of the interceptor 350 operates in user-mode203. In other embodiments, the client agent 120 operates in user-mode203 but interfaces via the interceptor 350 to a kernel-mode driver,process, service, task or portion of the operating system, such as toobtain a kernel-level data structure 225. In further embodiments, theinterceptor 350 is a user-mode application or program, such asapplication.

In one embodiment, the interceptor 350 intercepts any transport layerconnection requests. In these embodiments, the interceptor 350 executetransport layer application programming interface (API) calls to set thedestination information, such as destination IP address and/or port to adesired location for the location. In this manner, the interceptor 350intercepts and redirects the transport layer connection to a IP addressand port controlled or managed by the interceptor 350 or client agent120. In one embodiment, the interceptor 350 sets the destinationinformation for the connection to a local IP address and port of theclient 102 on which the client agent 120 is listening. For example, theclient agent 120 may comprise a proxy service listening on a local IPaddress and port for redirected transport layer communications. In someembodiments, the client agent 120 then communicates the redirectedtransport layer communication to the appliance 200.

In some embodiments, the interceptor 350 intercepts a Domain NameService (DNS) request. In one embodiment, the client agent 120 and/orinterceptor 350 resolves the DNS request. In another embodiment, theinterceptor transmits the intercepted DNS request to the appliance 200for DNS resolution. In one embodiment, the appliance 200 resolves theDNS request and communicates the DNS response to the client agent 120.In some embodiments, the appliance 200 resolves the DNS request viaanother appliance 200′ or a DNS server 106.

In yet another embodiment, the client agent 120 may comprise two agents120 and 120′. In one embodiment, a first agent 120 may comprise aninterceptor 350 operating at the network layer of the network stack 310.In some embodiments, the first agent 120 intercepts network layerrequests such as Internet Control Message Protocol (ICMP) requests(e.g., ping and traceroute). In other embodiments, the second agent 120′may operate at the transport layer and intercept transport layercommunications. In some embodiments, the first agent 120 interceptscommunications at one layer of the network stack 210 and interfaces withor communicates the intercepted communication to the second agent 120′.

The client agent 120 and/or interceptor 350 may operate at or interfacewith a protocol layer in a manner transparent to any other protocollayer of the network stack 310. For example, in one embodiment, theinterceptor 350 operates or interfaces with the transport layer of thenetwork stack 310 transparently to any protocol layer below thetransport layer, such as the network layer, and any protocol layer abovethe transport layer, such as the session, presentation or applicationlayer protocols. This allows the other protocol layers of the networkstack 310 to operate as desired and without modification for using theinterceptor 350. As such, the client agent 120 and/or interceptor 350can interface with the transport layer to secure, optimize, accelerate,route or load-balance any communications provided via any protocolcarried by the transport layer, such as any application layer protocolover TCP/IP.

Furthermore, the client agent 120 and/or interceptor may operate at orinterface with the network stack 310 in a manner transparent to anyapplication, a user of the client 102, and any other computing device,such as a server, in communications with the client 102. The clientagent 120 and/or interceptor 350 may be installed and/or executed on theclient 102 in a manner without modification of an application. In someembodiments, the user of the client 102 or a computing device incommunications with the client 102 are not aware of the existence,execution or operation of the client agent 120 and/or interceptor 350.As such, in some embodiments, the client agent 120 and/or interceptor350 is installed, executed, and/or operated transparently to anapplication, user of the client 102, another computing device, such as aserver, or any of the protocol layers above and/or below the protocollayer interfaced to by the interceptor 350.

The client agent 120 includes an acceleration program 302, a streamingclient 306, a collection agent 304, and/or monitoring agent 197. In oneembodiment, the client agent 120 comprises an Independent ComputingArchitecture (ICA) client, or any portion thereof, developed by CitrixSystems, Inc. of Fort Lauderdale, Fla., and is also referred to as anICA client. In some embodiments, the client 120 comprises an applicationstreaming client 306 for streaming an application from a server 106 to aclient 102. In some embodiments, the client agent 120 comprises anacceleration program 302 for accelerating communications between client102 and server 106. In another embodiment, the client agent 120 includesa collection agent 304 for performing end-point detection/scanning andcollecting end-point information for the appliance 200 and/or server106.

In some embodiments, the acceleration program 302 comprises aclient-side acceleration program for performing one or more accelerationtechniques to accelerate, enhance or otherwise improve a client'scommunications with and/or access to a server 106, such as accessing anapplication provided by a server 106. The logic, functions, and/oroperations of the executable instructions of the acceleration program302 may perform one or more of the following acceleration techniques: 1)multi-protocol compression, 2) transport control protocol pooling, 3)transport control protocol multiplexing, 4) transport control protocolbuffering, and 5) caching via a cache manager. Additionally, theacceleration program 302 may perform encryption and/or decryption of anycommunications received and/or transmitted by the client 102. In someembodiments, the acceleration program 302 performs one or more of theacceleration techniques in an integrated manner or fashion.Additionally, the acceleration program 302 can perform compression onany of the protocols, or multiple-protocols, carried as a payload of anetwork packet of the transport layer protocol.

The streaming client 306 comprises an application, program, process,service, task or executable instructions for receiving and executing astreamed application from a server 106. A server 106 may stream one ormore application data files to the streaming client 306 for playing,executing or otherwise causing to be executed the application on theclient 102. In some embodiments, the server 106 transmits a set ofcompressed or packaged application data files to the streaming client306. In some embodiments, the plurality of application files arecompressed and stored on a file server within an archive file such as aCAB, ZIP, SIT, TAR, JAR or other archive. In one embodiment, the server106 decompresses, unpackages or unarchives the application files andtransmits the files to the client 102. In another embodiment, the client102 decompresses, unpackages or unarchives the application files. Thestreaming client 306 dynamically installs the application, or portionthereof, and executes the application. In one embodiment, the streamingclient 306 may be an executable program. In some embodiments, thestreaming client 306 may be able to launch another executable program.

The collection agent 304 comprises an application, program, process,service, task or executable instructions for identifying, obtainingand/or collecting information about the client 102. In some embodiments,the appliance 200 transmits the collection agent 304 to the client 102or client agent 120. The collection agent 304 may be configuredaccording to one or more policies of the policy engine 236 of theappliance. In other embodiments, the collection agent 304 transmitscollected information on the client 102 to the appliance 200. In oneembodiment, the policy engine 236 of the appliance 200 uses thecollected information to determine and provide access, authenticationand authorization control of the client's connection to a network 104.

In one embodiment, the collection agent 304 comprises an end-pointdetection and scanning mechanism, which identifies and determines one ormore attributes or characteristics of the client. For example, thecollection agent 304 may identify and determine any one or more of thefollowing client-side attributes: 1) the operating system an/or aversion of an operating system, 2) a service pack of the operatingsystem, 3) a running service, 4) a running process, and 5) a file. Thecollection agent 304 may also identify and determine the presence orversions of any one or more of the following on the client: 1) antivirussoftware, 2) personal firewall software, 3) anti-spam software, and 4)internet security software. The policy engine 236 may have one or morepolicies based on any one or more of the attributes or characteristicsof the client or client-side attributes.

In some embodiments, the client agent 120 includes a monitoring agent197 as discussed in conjunction with FIGS. 1D and 2B. The monitoringagent 197 may be any type and form of script, such as Visual Basic orJava script. In one embodiment, the monitoring agent 129 monitors andmeasures performance of any portion of the client agent 120. Forexample, in some embodiments, the monitoring agent 129 monitors andmeasures performance of the acceleration program 302. In anotherembodiment, the monitoring agent 129 monitors and measures performanceof the streaming client 306. In other embodiments, the monitoring agent129 monitors and measures performance of the collection agent 304. Instill another embodiment, the monitoring agent 129 monitors and measuresperformance of the interceptor 350. In some embodiments, the monitoringagent 129 monitors and measures any resource of the client 102, such asmemory, CPU and disk.

The monitoring agent 197 may monitor and measure performance of anyapplication of the client. In one embodiment, the monitoring agent 129monitors and measures performance of a browser on the client 102. Insome embodiments, the monitoring agent 197 monitors and measuresperformance of any application delivered via the client agent 120. Inother embodiments, the monitoring agent 197 measures and monitors enduser response times for an application, such as web-based or HTTPresponse times. The monitoring agent 197 may monitor and measureperformance of an ICA or RDP client. In another embodiment, themonitoring agent 197 measures and monitors metrics for a user session orapplication session. In some embodiments, monitoring agent 197 measuresand monitors an ICA or RDP session. In one embodiment, the monitoringagent 197 measures and monitors the performance of the appliance 200 inaccelerating delivery of an application and/or data to the client 102.

In some embodiments and still referring to FIG. 3, a first program 322may be used to install and/or execute the client agent 120, or portionthereof, such as the interceptor 350, automatically, silently,transparently, or otherwise. In one embodiment, the first program 322comprises a plugin component, such an ActiveX control or Java control orscript that is loaded into and executed by an application. For example,the first program comprises an ActiveX control loaded and run by a webbrowser application, such as in the memory space or context of theapplication. In another embodiment, the first program 322 comprises aset of executable instructions loaded into and run by the application,such as a browser. In one embodiment, the first program 322 comprises adesigned and constructed program to install the client agent 120. Insome embodiments, the first program 322 obtains, downloads, or receivesthe client agent 120 via the network from another computing device. Inanother embodiment, the first program 322 is an installer program or aplug and play manager for installing programs, such as network drivers,on the operating system of the client 102.

D. Systems and Methods for Content Injection

Referring now to FIG. 4, a system 400 for injecting content into aresponse communicated from a server 106 to a client 102 over networks104, 104′ is depicted. In brief overview, the system 400 includes aclient 102, a server 106 and an appliance 200. The appliance 200 mayhave an integrated packet engine 240 to modify a response 405 from theserver and provide a modified response 420 to a browser 401 of theclient 102. The engine 240 may inject content into a prebody 421 or apostbody 422 of the response 405 to form the modified response 420. Theengine 240 may inject content into a response 405 responsive toinjection policies 415 of a policy engine 236. For example, theinjection policies 415 may include policies 416 based on the requestand/or policies 417 based on the response. The engine may inject intothe response one or more variables from a variable store 410. In somecases, a server 106A may include a performance monitoring agent 197 thatuses the modified response 420 to determine performance of the systemwith and without the appliance 200, such as by providing a report 425.

Still referring to FIG. 4A, in one embodiment, the appliance 200comprises an integrated package engine 240. The packet engine 240 of theappliance performs or otherwise provides any type and form of contentinjection into the response 405 received from the server 106. Theintegrated package engine 240 and the appliance 200 may include any ofthe embodiments discussed above in connection with FIG. 2A. In furtherdetails, in one embodiment, the integrated packet engine 240 may injectcontent into the response 405 by adding a prebody 421. In anotherembodiment, the packet engine 240 may inject content into the response405 by adding a postbody 422. In still another embodiment, the packetengine 240 may inject a prebody 421 and a postbody 422 into the response405. In some embodiments, the packet engine 240 may replace an existingprebody and/or an existing postbody in the response 405 with a newprebody 421 and/or a new postbody 422. In other embodiments, the packetengine 240 may modify the existing prebody and/or the existing postbodyin the response 405. In some embodiments, the packet engine 240 maymodify the body of the response 405. In some other embodiments, thepacket engine 240 may modify the header of the response 405. In oneembodiment, the packet engine 240 copies the network packet containingthe prebody and/or the postbody and modifies the copy to create a newpacket. In another embodiment, the packet engine 240 changes the payloadof an existing packet to include injected content. In one embodiment,the packet engine 240 injects values of variables present in the prebodyand/or the postbody of the response 405. In some embodiments, the packetengine 240 may inject content into any layer of a network packet. Inother embodiments, the packet engine 240 may inject content into aresponse 405 as a part of any protocol. In still other embodiments, thepacket engine 240 injects content into a response 405 by performing oneor more of the following: adding a variable, modifying a variable,assigning a value for a variable, modifying a value for a variable,replacing a variable or a value for a variable and deleting a variableor a value for a variable.

The appliance and/or packet engine 240 may create, modify, maintain orotherwise provide any number of variables in a variable store 410. Avariable may include any data structure or element for holding a valuerepresenting an operational or performance characteristic of any portionof the system 400. In one embodiment, the variable uniquely identifiesthe appliance 200. In another embodiment, the variable uniquelyidentifies a HTTP transaction between the client 102 and a server 106.In still other embodiments, the variable may be a timestamp storing oneor more of the following: time since the appliance 200 is running, timewhen the appliance 200 receives the first and last byte of the requestfrom the client 102, time when the appliance 200 forwards the first andlast byte of the client request to a server 106, time when the appliance200 receives the first and last byte of the response from the server 106and time when the appliance 200 forwards the first and last byte of theresponse from the server 106 to the client 102. In some of theseembodiments, the time is offset to Universal Coordinated Time (UTC). Insome embodiments, the variables may be created by the appliance 200 orany other software or hardware of the system 400. In one embodiment, thevariables may be obtained from a portion of a network packet. In otherembodiments, the variables may be defined by the user. In oneembodiment, the variables store values of parameters of the monitoringagent 197. In another embodiment, the variables store values pertainingto a function or an operation of the appliance 200 such as the functionsidentified and described in conjunction with FIG. 2B including loadbalancing, traffic management, acceleration, and switching. In someother embodiments, the variables may store values of other parametersassociated with a transaction between the client 102 and the server 106.

The variable store 410 may include any type and form of storage ormemory for holding one or more variables. In one embodiment, thevariable store 410 is an internal database residing within the appliance200. In another embodiment, the variable store 410 is a remote databasethat communicates with the appliance 200. In still another embodiment,the variable store 410 is created and maintained in a memory locationduring operation of the appliance. In yet another embodiment, thevariable store 410 is retained in a memory location when the appliance200 is not operational. In some embodiments, the variable store 410resides in a file system of the appliance 200. In other embodiments, thevariable store 410 is present on a disk on the appliance 200. In oneembodiment, the variable store 410 maintains a set of variables and/orvalues of the variables.

The appliance and/or packet engine may inject content or operateresponsive to a policy engine 236. The policy engine 236 may include anyof the embodiments discussed in connection with FIG. 2A. The policyengine 236 may include any type and form of injection policies 415directing or governing the behavior of the appliance 200 with respect toinjecting content. The injection policies 415 may be any type and formof policies for controlling, directing and managing injection of contentinto requests and/or responses communicated between a client and aserver. In some embodiments, the injection policies 415 may governfunctionalities of the appliance 200 based on one or more attributes ofa request and/or a response including: user information, temporalinformation, type of client device, location of client device, type ofserver and location of server. In some embodiments, an injection policy415 governs or controls which request policies 416 and/or responsepolicies 417 to use for a client, server, user, network, connection orsession. In one embodiment, the injection policies 415 comprise requestpolicies 416 and/or response policies 417. The request policies 416 andresponse policies 417 may include embodiments of a policy as describedin details in connection with FIG. 2A.

A request policy 416 is evaluated by the appliance 200 when a requestfrom a client 102 is received at the appliance 200. In one embodiment,the request policy 416 may prompt the appliance 200 to monitor atransaction associated with the request arriving from the client 102. Inanother embodiment, the request policy 416 may prompt the appliance 200to forward the request to the server 106 without taking any action. Instill another embodiment, the request policy 416 may instruct theappliance 200 to block the request from the client 102 from reaching theserver 106. In yet another embodiment, the request policy 416 modifiesthe request from the client 102 before forwarding the request to theserver 106. In some embodiments, the request policy may be evaluatedbased on information obtained from the request including: the userissuing the request, the browser 401 from which the request is issued,the client 102, the network 104 via which the request reaches theappliance 200 and any header, URL or flag that is present in any portionof a network packet. In one embodiment, the request policy 416 directsthe appliance 200 to inject content into the response 405 received forthe request. In another embodiment, the request policy 416 determineswhich response policy to apply to the response. In some embodiments, therequest policy determines the content such as the prebody 421 orpostbody 422 to inject into the response 405.

A response policy 417 may be evaluated by the appliance 200 when theserver response 405 is received at the appliance 200. In someembodiments, the response policy 417 prompts the appliance 200 to takean action on the server response 405. In one of these embodiments, theresponse policy 417 prompts the appliance 200 to add, modify or replacethe prebody 421 and/or the postbody 422 of the response 405 to createthe modified response 420. In another of these embodiments, the decisionto add, modify or replace the prebody 421 and/or the postbody 422 istaken based on evaluating the request policy 416 and the response policy417.

The appliance 200 and/or engine 240 may inject or otherwise modify anytype and form of the response 405 originating from a server 106. In oneembodiment, the server 106 transmits the response 405 responsive toreceiving a request originating from the client 102. In one embodiment,the server response 405 is a document created using a markup languagesuch as XML, HTML or XHTML. In another embodiment, the server response405 comprises a cascading style sheet (CSS) and metadata. In someembodiments, the server response 405 comprises a script such asJavaScript or AJAX. In some embodiments, the server response 405 maycomprise one or more of the following: static images, animated images,audio files and video files. In one of these embodiments, the staticimage is a raster graphic format such as GIF, JPEG or PNG. In another ofthese embodiments, the static image is a vector format such as SVGFlash. In still another embodiment, the animated image is an animatedGIF image, a Java applet or a Shockwave image. In yet anotherembodiment, the audio file may be of one of a plurality of formatsincluding MIDI, WAV, M3U and MP3. In another embodiment, the video filemay be of one of a plurality of formats including WMV, RM, FLV, MPG andMOV. In one embodiment, the server response 405 may comprise interactivetext, illustrations and buttons.

In one embodiment, the appliance 200 injects content into the serverresponse 405 and transmits a modified response 420 to the client 102. Inone embodiment, the content injection includes addition of a prebody 421at the beginning of the original server response 405. In anotherembodiment, the content injection includes addition of a postbody 422 atthe end of the original server response 405. In still anotherembodiment, the content injection includes addition of both the prebody421 and the postbody 422 of the original server response 405. In someembodiments, the server response 405 comprises a pre body and/or apostbody. In one of these embodiments, the appliance 200 modifies theprebody and/or postbody in the response 405. In another embodiment, theappliance 200 replaces the existing prebody and/or the existing postbodyin the response 405 with the prebody 421 and/or the postbody 422,respectively. In one embodiment, the prebody 421 and postbody 422comprise a script such as JavaScript or AJAX. In another embodiment, theprebody 421 and postbody 422 may comprise one or more of the pluralityof internal variables and timestamps described above. In still anotherembodiment, the prebody 421 and postbody 422 comprise script based onURL rewrite. In some embodiments, the response 405 may include one ormore variables that are referenced in the variable store. In one ofthese embodiments, the appliance 200 injects the value of the one ormore variables in the response 405.

In some cases, the appliance 200 modifies the response 405 to create themodified response 420. In one embodiment, the modified response 420 maycomprise a prebody 421 which is added, modified or replaced by theappliance 200. In another embodiment, the modified response 420 maycomprise a postbody 422 which is added, modified or replaced by theappliance 200. In still another embodiment, the modified response 420may have a prebody and a postbody which are added, modified or replacedby the appliance 200. In some embodiments, the modified response maycomprise additional content which is not part of the prebody 421 or thepostbody 422. In one of these embodiments, the additional content mayinclude: an image, a video clip, text, sponsored advertisement material,and other objects and entities. In one embodiment, the modified responsemay comprise portions written in a markup language different from themarkup language used in the response 405. In another embodiment, themodified response 420 may have values inserted for variables referencedin the response 405.

Based on the modified response 420, the performance monitoring agent 197monitors the performance of the appliance 200. In one embodiment, theperformance monitoring agent 197 may reside on a server 106A. In anotherembodiment, the agent 197 may reside on the client machine 102. In oneembodiment, the agent 197 compares the performance of the system 400with and without the appliance 200. In one embodiment, the report 425may include comparison on the time required to load a webpage with andwithout the appliance 200. In another embodiment, the report 425 mayinclude comparison of the time taken to deliver an application or filewith and without the appliance 200. In still another embodiment, thereport 425 may include details on improvement of application performanceon using the appliance 200. In yet another embodiment, the report 425may include comparative performance of streaming applications and/orremote desktop environments with and without the appliance 200. In otherembodiments, the report 425 may include any parameter or comparativeanalysis pertaining to the use of the appliance 200 in the system 400.In one embodiment, the report 425 is generated at predeterminedintervals. In another embodiment, the report 425 is generated on an adhoc basis. In still another embodiment, the report 425 is generated asrequested by a user or administrator monitoring the performance of theappliance 200 and/or the system 400.

In example operation, a user of the client machine 102 requests awebpage from the server 106 using the browser 401. The client 102transmits the request over the network 104 and the integrated packetengine 240 intercepts the request. The integrated packet engine 240communicates with the policy engine 236 to evaluate the injectionpolicies 415. The request policies 416 are evaluated by the policyengine 236. Based on a request policy 416, if the policy engine 236decides that a timestamp variable be tracked for the request, theintegrated packet engine 240 fetches a corresponding value of thevariable from the variable store 410. The request is then forwarded tothe server 106 via the network 104′. The server 106 transmits the serverresponse 405 back to the appliance 200 upon receiving the request. Theintegrated packet engine 240 receives the server response 405 andcommunicates with the policy engine 236 to evaluate response policies417. Based on a response policy 417, the policy engine directs theintegrated packet engine 240 to inject content into the response 405. Inone embodiment, the injected content may comprise a prebody 421 and apostbody 422 having values for one or more variables fetched from thevariable store 410. The appliance transmits the modified response 420 tothe client 102 over the network 104. The client 102 forwards informationin the modified response to the performance monitoring agent 197 whichmay reside on the server 106A. The agent 197 stores and analyzes datareceived from the client 102 and generates the reports 425.

Referring now to FIG. 4B, another embodiment 400′ of the system 400 isdepicted. In this embodiment 400′, the variable store 410 and the policyengine 236 reside on the client machine 102. The variable store 410 andthe policy engine 236 communicate with a client agent 120 to injectcontent into the server response 405. The client agent 120 may compriseany portion or embodiments of the integrated packet engine 240 forperforming or providing content injection in accordance with theoperations described herein. The client machine 102 communicates withthe server 106 over the network 104. In one embodiment, the performancemonitoring agent 197 (not shown) may reside on the client machine. Inanother embodiment, the agent 197 may reside on a server 106A (notshown). In still another embodiment 400″, the variable store 410 and thepolicy engine 236 reside on the server 106 as depicted in FIG. 4C. Inthis embodiment 400″, the variable store 410 and the policy engine 236communicate with an agent 430 to inject content into the server response405. The agent 430 may comprise any portion or embodiments of theintegrated packet engine 240 for performing or providing contentinjection in accordance with the operations described herein. In yetother embodiments the system 400, as described in details with referenceto FIG. 4A, may be deployed in other configurations. In someembodiments, one or more components of the system 400 distributed acrossany combination of the client 102, the server 106 and the appliance 200.

Referring now to FIG. 5, a flow diagram for an embodiment of a method500 to inject content into a server response is depicted. In briefoverview, an appliance 200 receives (step 510) a request for a webpageoriginating from a client 102 and directed to a server 106. Theappliance 200 determines if the request matches a request policy 416.The appliance 200 receives (step 530) the server response 405 responsiveto forwarding the request to the server 106. The appliance 200determines (step 540) if the response 405 matches a response policy 417.The appliance 200 modifies (step 540) the response in accordance withthe request policy 416 and/or the response policy 417. The appliance 200transmits (step 550) the modified response 420 to the client 102.

The appliance 200 may receive (step 510) the request originating fromthe client in a plurality of forms. In one embodiment, the request is aHyper Text Transfer Protocol (HTTP) request originating from a useragent such as a web browser. In another embodiment, the client 102establishes a transmission control protocol (TCP) connection with theappliance 200 before sending the request. In some embodiments, anencryption layer may be present between the HTTP and TCP protocols. Inone of these embodiments, the encryption layer is a Secure Socket Layer(SSL) or Transport Layer Security (TLS) connection. In one embodiment,the received request may be a request for an application. In anotherembodiment, the received request may be a request for a server 106 toexecute an application on behalf of the client 102. In still anotherembodiment, the received request may be a request to stream anapplication to the client 102. In yet another embodiment, the receivedrequest may be a request to stream a desktop environment to the client102. In still another embodiment, the request may submit information tobe processed by a resource identified by the request.

The appliance 200 determines (step 520) if the request matches a requestpolicy 416. In one embodiment, the integrated packet engine 240communicates with the policy engine 236 to determine if the requestmatches a request policy 416. In another embodiment, if the policyengine 236 detects a matching request policy 416, the integrated packetengine communicates with the variable store 410 to retrieve and storethe values of one or more variables. In still another embodiment, theappliance 200 forwards the request to the server 106 after determiningif the request matches a request policy 416. The appliance 200 may useany portion of a network packet of the request to determine if a requestpolicy matches or corresponds to the request. In one embodiment, theappliance 200 uses the header of the network packet for the requestpolicy matching. In another embodiment, the appliance 200 uses thepayload portion of the network packet for the request policy matching.In still another embodiment, the appliance uses a network packet fromany protocol for the request policy matching. In yet another embodiment,the appliance 200 uses a network packet in any layer of the network forthe request policy matching.

Determining (step 520) the request policy 416 by the policy engine 236may comprise of additional steps as depicted in FIG. 5B. The requestarrives (step 521) at the appliance 200. In one embodiment, theappliance 200 checks (step 522) if a policy hit has occurred. In anotherembodiment, the appliance checks for the policy hit in communicationwith a policy engine 236. In the absence of a matching policy, therequest is processed (step 523 a) and forwarded (step 529) to the server106. In one embodiment, in the absence of a matching policy, theprocessing (step 523 a) involves no further action by the appliance 200.In another embodiment, if a policy hit is evaluated (step 522), acontent injection session is created (step 523). In still anotherembodiment, content injection comprises injection of HTML content. Inyet another embodiment, the appliance 200 performs a check (step 524)for a first byte of the request. If the first byte of request isdetected, a variable to store the time at which the appliance 200receives the first byte of request is generated (step 524 a). If thefirst byte of request is not detected, the appliance 200 performs acheck (step 525) for the last byte of the request. In one embodiment,the appliance 200 checks for the last byte of the request upongenerating the variable to store the time corresponding to the firstbyte of the request. If the last byte of the request is detected, avariable to store the time at which the appliance 200 receives the lastbyte of request is generated (step 525 a). If the last byte of therequest is not detected, the appliance 200 further processes (step 526)the request in preparation of forwarding the request to the server 106.In another embodiment, the request is further processed (step 526) bythe appliance 200 upon generating the variable to store the timecorresponding to the last byte of the request. In one embodiment, theappliance 200 checks (step 527) for the first byte of the request to beforwarded to the server 106. If the first byte of the request to beforwarded to the server 106 is detected, a variable to store the time atwhich the appliance 200 sends the first byte of request to the server106 is generated (step 527 a). If the first byte of request to beforwarded to the server 106 is not detected, the appliance 200 performsa check (step 528) for the last byte of the request to be forwarded tothe server 106. In one embodiment, the appliance 200 checks for the lastbyte of the request to be forwarded to the server 106 upon generatingthe variable to store the time corresponding to the first byte of theforwarded request. If the last byte of the request to be forwarded tothe server 106 is detected, a variable to store the time at which theappliance 200 sends the last byte of the request is generated (step 528a). If the last byte of the request is not detected, the appliance 200forwards (step 529) the request to the server 106. In anotherembodiment, the request is forwarded (step 529) by the appliance 200upon generating the variable to store the time corresponding to the lastbyte of the forwarded request.

The server response 405 is received (step 530) at the appliance 200 uponthe server transmitting the response 405. The server response 405 isdescribed above in details with reference to FIG. 4A. In one embodiment,the response is received via a network 104 as described in details withreference to FIG. 4A. In another embodiment, the response is receivedvia a plurality of proxies and networks 104. In one embodiment, theserver 106 streams an application in response to receiving the clientrequest. In another embodiment, the server 106 streams a file or anyother resource in response to receiving the client request. In stillanother embodiment, the server streams a file or resource related to aprotocol such as the Independent Computing Architecture (ICA) developedby Citrix Systems Inc. of Ft. Lauderdale, Fla. In one embodiment, theresponse 405 comprises one or more network packets.

The appliance 200 determines if the server response 405 matches aresponse policy 417. In one embodiment, the integrated packet engine 240communicates with the policy engine 236 to determine the response policy417. The appliance 200 may use any portion of a network packet of theresponse to determine if a response policy matches or corresponds to therequest. In one embodiment, the appliance 200 uses the header of thenetwork packet for the response policy matching. In another embodiment,the appliance 200 uses the payload portion of the network packet for theresponse policy matching. In still another embodiment, the applianceuses a network packet from any protocol for the response policymatching. In yet another embodiment, the appliance 200 uses a networkpacket in any layer of the network for the response policy matching. Inanother embodiment, if a matching response policy is found, theappliance 200 modifies the server response 405 by injecting content intothe response 405. In still another embodiment, the appliance 200modifies the response 405 by inserting or modifying values of variablesretrieved from the variable store 410.

Determining (step 540) the response policy at the appliance 200 maycomprise of additional steps as depicted in FIG. 5C. In one embodiment,the appliance 200 modifies the response 405 to insert content specifiedby the policy engine 236, the content comprising values for one or morevariables obtained by the appliance 200 in communication with a variablestore 410. Once the server response 405 arrives (step 541) at theappliance 200, the appliance 200 checks (step 542) for a policy hit. Inone embodiment, if a policy hit is not detected, the appliance 200proceeds to execute the step 550 as shown in FIG. 5A. If a policy hit isdetected, the appliance 200 checks (step 543) for the first byte of theresponse 405. If the first byte of the response is detected, theappliance records (step 543 a) a value of a variable corresponding tothe time the appliance 200 receives the first byte of the response. Inone embodiment, a variable corresponding to the time the appliance 200forwards the first byte of the response to the client 102 is set to therecorded value. In one embodiment, the appliance 200 checks (step 543 b)for a policy to inject a prebody 421. If a policy to inject the prebody421 is detected, the appliance 200 replaces (step 543 c) the variablesin the prebody by the actual recorded values and inserts (step 543 c)the content at the beginning of the response 405. In one embodiment, ifthe check (step 543) does not detect the first byte of the response, theappliance 200 proceeds to check (step 544) for the last byte of theresponse 405. In another embodiment, the appliance 200 checks for thelast byte of the response if the step 543 b does not indicate a policyto inject a prebody 421. In still another embodiment, the appliance 200checks for the last byte of the response upon executing step 543 c. Ifthe last byte of the response is detected, the appliance records (step544 a) a value of a variable corresponding to the time the appliance 200receives the last byte of the response. In one embodiment, a variablecorresponding to the time the appliance 200 forwards the last byte ofthe response to the client 102 is set to the recorded value. In oneembodiment, the appliance 200 checks (step 544 b) for a policy to injecta postbody 422. If a policy to inject the prebody 422 is detected, theappliance 200 replaces (step 544 c) the variables in the postbody by theactual recorded values and inserts (step 544 c) the content at the endof the response 405. In one embodiment, if the check (step 544) does notdetect the last byte of the response, the appliance 200 executes step550 as shown in FIG. 5A. In another embodiment, the appliance 200executes step 550 if the step 544 b does not indicate a policy to injecta postbody 422. In still another embodiment, the appliance 200 executesstep 550 upon executing step 544 c.

The appliance 200 transmits (step 550) the modified response 420 to theclient 102 over the network 104. The modified response 420 is describedabove in details with reference to FIG. 4A. In some embodiments, theremay be one or more proxies and/or one or more networks 104 between theappliance 200 and the client 102. In one of these embodiments, themodified response 420 may be transmitted to the client 102 via theserver 106′ on which the performance monitoring agent 197 resides. Inanother of these embodiments, the server 106′ may be connected to thenetwork 104 that connects the appliance 200 and the client 102.

In view of the structure, functions and apparatus of the systems andmethods described here, the present solution provides a dynamic,flexible and configurable system for injecting content into a serverresponse to a client request. Having described certain embodiments ofmethods and systems for the content injection, it will now becomeapparent to one of skill in the art that other embodiments incorporatingthe concepts of the invention may be used. Therefore, the inventionshould not be limited to certain embodiments, but rather should belimited only by the spirit and scope of the following claims:

What is claimed is:
 1. A method comprising: (a) identifying, by a policyengine of an intermediary, a policy to apply to a communication betweena client and a server, the policy identifying a plurality of variablesfor which a value is to be determined by the intermediary and includedin the communication; (b) determining, by the intermediary, a first timeof forwarding a first byte of the communication between the client andthe server forwarded by the intermediary and a second time of forwardinga last byte of the communication between the client and the serverforwarded by the intermediary; (c) modifying, by the intermediary, thecommunication to include the first time as a first value for a firstvariable of the plurality of variables and the second time as a secondvalue for a second variable for the plurality of variables; and (d)forwarding, by the intermediary, the modified communication.
 2. Themethod of claim 1, wherein the policy specifies content to include intothe communication, the content identifying the plurality of variables.3. The method of claim 2, wherein the content of the policy comprisesone of a HyperText Transfer Protocol prebody, postbody or a header. 4.The method of claim 1, wherein (a) further comprises identifying, by theintermediary, that content of the communication matches an expression ofthe policy.
 5. The method of claim 1, wherein (c) further comprisesmodifying, by the intermediary, the communication to include one of thefollowing: an identifier of the intermediary, a transaction identifierfor the communication or a system uptime.
 6. The method of claim 1,wherein the communication comprises one of a response from the server tothe client or a request from the client to the server.
 7. The method ofclaim 1, wherein the intermediary is a device intermediary to the clientand the server.
 8. A method comprising: (a) identifying, by a policyengine of an intermediary, a policy to apply to a communication betweena client and a server, the policy identifying a plurality of variablesfor which a value is to be determined by the intermediary and includedin the communication; (b) determining, by the intermediary, a first timeof receipt of a first byte of the communication between the client andthe server received by the intermediary and a second time of receipt ofa last byte of the communication between the client and the serverreceived by the intermediary; (c) modifying, by the intermediary, thecommunication to include the first time as a first value for a firstvariable of the plurality of variables and the second time as a secondvalue for a second variable for the plurality of variables; and (d)forwarding, by the intermediary, the modified communication.
 9. Themethod of claim 8, wherein the policy specifies content to include intothe communication, the content identifying the plurality of variables.10. The method of claim 9, wherein the content of the policy comprisesone of a HyperText Transfer Protocol prebody, postbody or a header. 11.The method of claim 8, wherein (a) further comprises identifying, by theintermediary, that content of the communication matches an expression ofthe policy.
 12. The method of claim 8, wherein (c) further comprisesmodifying, by the intermediary, the communication to include one of thefollowing: an identifier of the intermediary, a transaction identifierfor the communication or a system uptime.
 13. The method of claim 8,wherein the communication comprises one of a response from the server tothe client or a request from the client to the server.
 14. The method ofclaim 8, wherein the intermediary is a device intermediary to the clientand the server.
 15. A system comprising: a device intermediary to aplurality of clients and one or more servers; a policy engine of thedevice configured to identify a policy to apply to a communicationbetween a client and a server, the policy identifying a plurality ofvariables for which a value is to be determined by the intermediary andincluded in the communication; wherein the device is configured to:determine a first timestamp of a first byte of the communication betweenthe client and server traversing the device and a second timestamp of alast byte of the communication between the client and server traversingthe device; modify the communication to include the first timestamp as afirst value for a first variable of the plurality of variables and thesecond timestamp as a second value for a second variable for theplurality of variables; and forward the modified communication.
 16. Thesystem of claim 15, wherein the policy specifies content to include intothe communication, the content identifying the plurality of variables.17. The system of claim 16, wherein the content of the policy comprisesone of a HyperText Transfer Protocol prebody, postbody or a header. 18.The system of claim 15, whether the device is further configured toidentify that, content of the communication matches an expression of thepolicy.
 19. The system of claim 15, whether the device is furtherconfigured to modify the communication to include one of the following:an identifier of the intermediary, a transaction identifier for thecommunication or a system uptime.
 20. The system of claim 15, whereinthe communication comprises one of a response from the server to theclient or a request from the client to the server.